Context#each_section yields only display? items

Context#each_section yields all constants and attributes,
but RDoc treats only displayed items for documentation.
The Darkfish template,
lib/rdoc/generator/template/darkfish/class.rhtml,
it retrieves items only what #display? is true inside #each_section.
It's strange behavior.
I think #each_section should return only displayed items.
This commit fixes it.

Author: aycabta

lib/rdoc/context.rb

@@ -762,7 +762,7 @@ def each_section # :yields: section, constants, attributes
     attributes.default = []
 
     sort_sections.each do |section|
-      yield section, constants[section].sort, attributes[section].sort
+      yield section, constants[section].select(&:display?).sort, attributes[section].select(&:display?).sort
     end
   end
 

lib/rdoc/generator/template/darkfish/class.rhtml

@@ -26,8 +26,6 @@
   </section>
 
   <% klass.each_section do |section, constants, attributes| %>
-  <% constants = constants.select { |const| const.display? } %>
-  <% attributes = attributes.select { |attr| attr.display? } %>
   <section id="<%= section.aref %>" class="documentation-section">
     <% if section.title then %>
     <header class="documentation-section-title">