merge revision(s) 42541: [Backport #8903]

	* object.c (Init_Object): undef Module#prepend_features on Class, as
	  well as Module#append_features.  [Fixes GH-376]

	* test_class.rb: Added test for above. And ensure type checking
	  on similar methods as module_function.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@42936 b2dd03c8-39d4-4d8f-98ff-823fe69b080e