Extracted common code from checkDefaultedNameConflict method in UmpleInternalParser_Code.ump and moved to be a method within UmpleModel in Umple_Code.ump in preparation for code changes related to issue 530

git-svn-id: http://umple.googlecode.com/svn/trunk@3915 6ebf9d09-8eb1-0036-9d08-68c07d1b990a