When specializing a generic the references from unitsyms to the loaded modules
	needs to be reestablished, so that "unitidentifier.identifier" can be used
	inside a generic without leading to an access violation.
	Only global units are checked, because a generic must not use symbols from the
	static symtable or from units used by the implementation section (the latter is 
	currently not checked)

+ added tests for the above problem for "normal" units as well as units with a namespace 

git-svn-id: trunk@20245 -