New Mind Procs/Fixes Borg memories after borging [NEEDS TESTING]

Adds remove_antag(specified_antag) which removes all references to an antag type inside a mind
Update mind.dm's href "clear" references to use remove_antag()
remove_antag() is designed to be run on a mind
adds remove_all_antag() which calls remove_antag() on all antag types possible
Borg's no longer retain memories after borging
wipe_memory() is just a quick shortcut for memory = null