Categories#parse now includes validation.

Simpler api to call from main app.rb

lib/jsduck/app.rb

@@ -73,7 +73,6 @@ module JsDuck
       @categories = Categories.new(get_doc_formatter, @relations)
       if @opts.categories_path
         @categories.parse(@opts.categories_path)
-        @categories.validate
       else
         @categories.auto_generate
       end

lib/jsduck/categories.rb

@@ -35,6 +35,8 @@ module JsDuck
           end.flatten
         end
       end
+
+      validate
     end
 
     # Expands class name like 'Foo.*' into multiple class names.