Fix safe Style/ColonMethodCall offenses

Caxlsx is using both `.` and `::`, 220 occurrences vs 280 to invoke
methods on `Axlsx` module.

This commit standardizes the approach towards `.`, which will also allow
shorter lines.

Performance is not affected

```
Comparison:
      Axlsx.validate:  8515252.3 i/s
     Axlsx::validate:  8512863.7 i/s - same-ish: difference falls within error 
```

9 files changed, 27 insertions, 27 deletions

diff --git a/test/drawing/tc_d_lbls.rb b/test/drawing/tc_d_lbls.rb
index 9bb2d4ba..c3172326 100644
--- a/test/drawing/tc_d_lbls.rb
+++ b/test/drawing/tc_d_lbls.rb
@@ -53,7 +53,7 @@ class TestDLbls < Test::Unit::TestCase
     doc = Nokogiri::XML(str)
 
     Axlsx.instance_values_for(@d_lbls).each do |name, value|
-      assert(doc.xpath("//c:#{Axlsx::camel(name, false)}[@val='#{value}']"), "#{name} is properly serialized")
+      assert(doc.xpath("//c:#{Axlsx.camel(name, false)}[@val='#{value}']"), "#{name} is properly serialized")
     end
   end
 end
diff --git a/test/tc_axlsx.rb b/test/tc_axlsx.rb
index f4f6a01d..66b12ff9 100644
--- a/test/tc_axlsx.rb
+++ b/test/tc_axlsx.rb
@@ -96,9 +96,9 @@ class TestAxlsx < Test::Unit::TestCase
   end
 
   def test_range_to_a
-    assert_equal([['A1', 'B1', 'C1']],                         Axlsx::range_to_a('A1:C1'))
-    assert_equal([['A1', 'B1', 'C1'], ['A2', 'B2', 'C2']],     Axlsx::range_to_a('A1:C2'))
-    assert_equal([['Z5', 'AA5', 'AB5'], ['Z6', 'AA6', 'AB6']], Axlsx::range_to_a('Z5:AB6'))
+    assert_equal([['A1', 'B1', 'C1']],                         Axlsx.range_to_a('A1:C1'))
+    assert_equal([['A1', 'B1', 'C1'], ['A2', 'B2', 'C2']],     Axlsx.range_to_a('A1:C2'))
+    assert_equal([['Z5', 'AA5', 'AB5'], ['Z6', 'AA6', 'AB6']], Axlsx.range_to_a('Z5:AB6'))
   end
 
   def test_sanitize_frozen_control_strippped
@@ -165,15 +165,15 @@ class TestAxlsx < Test::Unit::TestCase
   def test_escape_formulas
     Axlsx.instance_variable_set(:@escape_formulas, nil)
 
-    refute Axlsx::escape_formulas
+    refute Axlsx.escape_formulas
 
-    Axlsx::escape_formulas = true
+    Axlsx.escape_formulas = true
 
-    assert Axlsx::escape_formulas
+    assert Axlsx.escape_formulas
 
-    Axlsx::escape_formulas = false
+    Axlsx.escape_formulas = false
 
-    refute Axlsx::escape_formulas
+    refute Axlsx.escape_formulas
   ensure
     Axlsx.instance_variable_set(:@escape_formulas, nil)
   end
diff --git a/test/tc_package.rb b/test/tc_package.rb
index 75fe2cdf..9b057a94 100644
--- a/test/tc_package.rb
+++ b/test/tc_package.rb
@@ -319,8 +319,8 @@ class TestPackage < Test::Unit::TestCase
   end
 
   def test_name_to_indices
-    assert_equal([0, 0], Axlsx::name_to_indices('A1'))
-    assert_equal([0, 99], Axlsx::name_to_indices('A100'), 'needs to axcept rows that contain 0')
+    assert_equal([0, 0], Axlsx.name_to_indices('A1'))
+    assert_equal([0, 99], Axlsx.name_to_indices('A100'), 'needs to axcept rows that contain 0')
   end
 
   def test_to_stream
diff --git a/test/util/tc_mime_type_utils.rb b/test/util/tc_mime_type_utils.rb
index 16ba45cd..f990e8e2 100644
--- a/test/util/tc_mime_type_utils.rb
+++ b/test/util/tc_mime_type_utils.rb
@@ -14,11 +14,11 @@ class TestMimeTypeUtils < Test::Unit::TestCase
   def teardown; end
 
   def test_mime_type_utils
-    assert_equal('image/jpeg', Axlsx::MimeTypeUtils::get_mime_type(@test_img))
-    assert_equal('image/png', Axlsx::MimeTypeUtils::get_mime_type_from_uri(@test_img_url))
+    assert_equal('image/jpeg', Axlsx::MimeTypeUtils.get_mime_type(@test_img))
+    assert_equal('image/png', Axlsx::MimeTypeUtils.get_mime_type_from_uri(@test_img_url))
   end
 
   def test_escape_uri
-    assert_raise(URI::InvalidURIError) { Axlsx::MimeTypeUtils::get_mime_type_from_uri('| ls') }
+    assert_raise(URI::InvalidURIError) { Axlsx::MimeTypeUtils.get_mime_type_from_uri('| ls') }
   end
 end
diff --git a/test/workbook/tc_workbook.rb b/test/workbook/tc_workbook.rb
index 51fe3976..2422cc79 100644
--- a/test/workbook/tc_workbook.rb
+++ b/test/workbook/tc_workbook.rb
@@ -185,7 +185,7 @@ class TestWorkbook < Test::Unit::TestCase
   end
 
   def test_escape_formulas
-    Axlsx::escape_formulas = false
+    Axlsx.escape_formulas = false
     p = Axlsx::Package.new
     @wb = p.workbook
 
@@ -194,7 +194,7 @@ class TestWorkbook < Test::Unit::TestCase
     assert_false @wb.add_worksheet(escape_formulas: false).escape_formulas
     assert @wb.add_worksheet(escape_formulas: true).escape_formulas
 
-    Axlsx::escape_formulas = true
+    Axlsx.escape_formulas = true
     p = Axlsx::Package.new
     @wb = p.workbook
 
diff --git a/test/workbook/worksheet/tc_comment.rb b/test/workbook/worksheet/tc_comment.rb
index aa33dba4..80bd01cb 100644
--- a/test/workbook/worksheet/tc_comment.rb
+++ b/test/workbook/worksheet/tc_comment.rb
@@ -41,7 +41,7 @@ class TestComment < Test::Unit::TestCase
   end
 
   def test_vml_shape
-    pos = Axlsx::name_to_indices(@c1.ref)
+    pos = Axlsx.name_to_indices(@c1.ref)
 
     assert(@c1.vml_shape.is_a?(Axlsx::VmlShape))
     assert_equal(@c1.vml_shape.column, pos[0])
diff --git a/test/workbook/worksheet/tc_date_time_converter.rb b/test/workbook/worksheet/tc_date_time_converter.rb
index 5cc9d619..6d95b111 100644
--- a/test/workbook/worksheet/tc_date_time_converter.rb
+++ b/test/workbook/worksheet/tc_date_time_converter.rb
@@ -16,7 +16,7 @@ class TestDateTimeConverter < Test::Unit::TestCase
       "2006-02-01" => 38_749.0,
       "9999-12-31" => 2_958_465.0
     }.each do |date_string, expected|
-      serial = Axlsx::DateTimeConverter::date_to_serial Date.parse(date_string)
+      serial = Axlsx::DateTimeConverter.date_to_serial Date.parse(date_string)
 
       assert_equal expected, serial
     end
@@ -31,7 +31,7 @@ class TestDateTimeConverter < Test::Unit::TestCase
       "2006-02-01" => 37_287.0,
       "9999-12-31" => 2_957_003.0
     }.each do |date_string, expected|
-      serial = Axlsx::DateTimeConverter::date_to_serial Date.parse(date_string)
+      serial = Axlsx::DateTimeConverter.date_to_serial Date.parse(date_string)
 
       assert_equal expected, serial
     end
@@ -46,7 +46,7 @@ class TestDateTimeConverter < Test::Unit::TestCase
       "1900-01-01T12:00:00Z" => 2.5, # wrongly indicated as 1.5 in the spec!
       "9999-12-31T23:59:59Z" => 2_958_465.9999884
     }.each do |time_string, expected|
-      serial = Axlsx::DateTimeConverter::time_to_serial Time.parse(time_string)
+      serial = Axlsx::DateTimeConverter.time_to_serial Time.parse(time_string)
 
       assert_in_delta expected, serial, @margin_of_error
     end
@@ -61,7 +61,7 @@ class TestDateTimeConverter < Test::Unit::TestCase
       "1904-01-01T12:00:00Z" => 0.5000000,
       "9999-12-31T23:59:59Z" => 2_957_003.9999884
     }.each do |time_string, expected|
-      serial = Axlsx::DateTimeConverter::time_to_serial Time.parse(time_string)
+      serial = Axlsx::DateTimeConverter.time_to_serial Time.parse(time_string)
 
       assert_in_delta expected, serial, @margin_of_error
     end
@@ -72,9 +72,9 @@ class TestDateTimeConverter < Test::Unit::TestCase
     local = Time.parse "2012-01-01 09:00:00 +0900"
 
     assert_equal local, utc
-    assert_equal Axlsx::DateTimeConverter::time_to_serial(local) - (local.utc_offset.to_f / 86_400), Axlsx::DateTimeConverter::time_to_serial(utc)
+    assert_equal Axlsx::DateTimeConverter.time_to_serial(local) - (local.utc_offset.to_f / 86_400), Axlsx::DateTimeConverter.time_to_serial(utc)
     Axlsx::Workbook.date1904 = true
 
-    assert_equal Axlsx::DateTimeConverter::time_to_serial(local) - (local.utc_offset.to_f / 86_400), Axlsx::DateTimeConverter::time_to_serial(utc)
+    assert_equal Axlsx::DateTimeConverter.time_to_serial(local) - (local.utc_offset.to_f / 86_400), Axlsx::DateTimeConverter.time_to_serial(utc)
   end
 end
diff --git a/test/workbook/worksheet/tc_table_style_info.rb b/test/workbook/worksheet/tc_table_style_info.rb
index 6cb12b94..2e327a73 100644
--- a/test/workbook/worksheet/tc_table_style_info.rb
+++ b/test/workbook/worksheet/tc_table_style_info.rb
@@ -9,7 +9,7 @@ class TestTableStyleInfo < Test::Unit::TestCase
     40.times do
       @ws.add_row %w(aa bb cc dd ee ff gg hh ii jj kk)
     end
-    @table = @ws.add_table(Axlsx::cell_range([@ws.rows.first.cells.first, @ws.rows.last.cells.last], false), name: 'foo')
+    @table = @ws.add_table(Axlsx.cell_range([@ws.rows.first.cells.first, @ws.rows.last.cells.last], false), name: 'foo')
     @options =  { show_first_column: 1,
                   show_last_column: 1,
                   show_row_stripes: 1,
diff --git a/test/workbook/worksheet/tc_worksheet.rb b/test/workbook/worksheet/tc_worksheet.rb
index 4ec74efb..464d2e64 100644
--- a/test/workbook/worksheet/tc_worksheet.rb
+++ b/test/workbook/worksheet/tc_worksheet.rb
@@ -456,14 +456,14 @@ class TestWorksheet < Test::Unit::TestCase
   end
 
   def test_to_xml_string_with_illegal_chars
-    old = Axlsx::trust_input
-    Axlsx::trust_input = false
+    old = Axlsx.trust_input
+    Axlsx.trust_input = false
     nasties = "\v\u2028\u0001\u0002\u0003\u0004\u0005\u0006\u0007\u0008\u001f"
     @ws.add_row [nasties]
 
     assert_equal(0, @ws.rows.last.cells.last.value.index("\v"))
     assert_nil(@ws.to_xml_string.index("\v"))
-    Axlsx::trust_input = old
+    Axlsx.trust_input = old
   end
 
   def test_to_xml_string_with_newlines