* object.c: [DOC] Clarify Object#dup vs #clone [Bug #9128]
  Moving existing doc for this comparison to separate section of #dup
  Adding examples to document behavior of #dup with Module#extend.
  Based on a patch by stevegoobermanhill


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43747 b2dd03c8-39d4-4d8f-98ff-823fe69b080e