Removing Lang::activate, no issues in S 2.3 found.

If something similar should be needed again, we might use Lang::initialize() with Symphony 2.3. - Lang::activate() no longer exists.
Remove call-time pass-by-reference.

Call-time pass-by-reference made the field break in PHP 5.4, and it has been deprecated for a while. We don't need it anyway - the reference is in the function definitions.