preliminary voting/basic restarting

todo: fix timer not resetting on client
reset item spawns on server
give a few seconds warning before restart really happens
?
restart now resets ents, client-side stuff

still todo:
don't reassign teams on restart
don't kick bots on restart
use restart code in map change code instead of duplicating
?
don't auto-assign teams at restart
unbreak teaminfo, mapcrc on restartgame
don't kick AI on restartgame
Merge branch 'restartgame'