Support Commonmarker (lowercase m) from v1.x

Fixes lsegal#1528

Co-Authored-By: Andrew Haines <andrew@haines.org.nz>

Author: ParadoxV5

lib/yard/templates/helpers/html_helper.rb

@@ -89,6 +89,8 @@ def html_markup_markdown(text)
                              :tables,
                              :with_toc_data,
                              :no_intraemphasis).to_html
+        when 'Commonmarker'
+          Commonmarker.to_html(text) # GFM configs are on by default
         when 'CommonMarker'
           CommonMarker.render_html(text, %i[DEFAULT GITHUB_PRE_LANG], %i[autolink table])
         else

lib/yard/templates/helpers/markup_helper.rb

@@ -30,6 +30,7 @@ def clear_markup_cache
           {:lib => :maruku, :const => 'Maruku'},
           {:lib => :'rpeg-markdown', :const => 'PEGMarkdown'},
           {:lib => :rdoc, :const => 'YARD::Templates::Helpers::Markup::RDocMarkdown'},
+          {:lib => :commonmarker, :const => 'Commonmarker'},
           {:lib => :commonmarker, :const => 'CommonMarker'}
         ],
         :textile => [

spec/templates/helpers/html_helper_spec.rb

@@ -158,7 +158,7 @@ def options
 
     it "creates tables (markdown specific)" do
       log.enter_level(Logger::FATAL) do
-        supports_table = %w(RedcarpetCompat Kramdown::Document CommonMarker)
+        supports_table = %w(RedcarpetCompat Kramdown::Document Commonmarker CommonMarker)
         unless supports_table.include?(markup_class(:markdown).to_s)
           pending "This test depends on a markdown engine that supports tables"
         end

spec/templates/markup_processor_integrations/markdown_spec.rb

@@ -82,7 +82,7 @@
     end
   end
 
-  describe 'CommonMarker', if:  RUBY_VERSION >= '2.3' do
+  describe 'Commonmarker', if:  RUBY_VERSION >= '2.3' do
     let(:markup) { :markdown }
     let(:markup_provider) { :commonmarker }