adding &defaultGenerate option to URL command line so we can force
the generate menu to preselect cpp for composite structure. This is used in
the user manual already. Also whenever a composite structure example
is selected in the example menu, the cpp default is suggested too


git-svn-id: http://umple.googlecode.com/svn/trunk@4289 6ebf9d09-8eb1-0036-9d08-68c07d1b990a