If your still tempted to change "/" to "." in MediaWiki think about this first: * it would be virtually impossible to find the occurences because you would need to search for "_" which is used about a zillion times per file * if you did ever succeed in making the change, you would have to redo the work from scratch every time MediaWiki changed (you of course couldn't guarantee there would not be other places to look each time), or you would be stuck forever on the release version you changed.
Don't think it's a good idea.