Extracted new_subclass_instance method to a module.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@8183 e93f8b46-1217-0410-a6f0-8f06a7374b81
resourcified enumerations

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@8189 e93f8b46-1217-0410-a6f0-8f06a7374b81