Limit aggravate to inside or outside of the Wizard's tower

There have been several comments on IRC how the Wizard is a very
light sleeper now; aggravate cast by monsters makes him wake up
and come out of the tower.  So, lets limit aggravate to either
outside or inside of the tower, depending on which side the player is.

include/extern.h

@@ -2677,6 +2677,7 @@ E void NDECL(amulet);
 E int FDECL(mon_has_amulet, (struct monst *));
 E int FDECL(mon_has_special, (struct monst *));
 E int FDECL(tactics, (struct monst *));
+E boolean FDECL(has_aggravatables, (struct monst *));
 E void NDECL(aggravate);
 E void NDECL(clonewiz);
 E int NDECL(pick_nasty);