Add HITOWNER flag, when set, allows a projectile to collide with its shooter.

src/actor.h

@@ -403,6 +403,7 @@ enum ActorFlag8
 	MF8_INSCROLLSEC		= 0x00000002,	// actor is partially inside a scrolling sector
 	MF8_BLOCKASPLAYER	= 0x00000004,	// actor is blocked by player-blocking lines even if not a player
 	MF8_DONTFACETALKER	= 0x00000008,	// don't alter the angle to face the player in conversations
+	MF8_HITOWNER		= 0x00000010,	// projectile can hit the actor that fired it
 };
 
 // --- mobj.renderflags ---

src/p_map.cpp

@@ -1554,8 +1554,8 @@ bool PIT_CheckThing(FMultiBlockThingsIterator &it, FMultiBlockThingsIterator::Ch
 
 		if (tm.thing->target != NULL)
 		{
-			if (thing == tm.thing->target)
-			{ // Don't missile self
+			if (thing == tm.thing->target && !(tm.thing->flags8 & MF8_HITOWNER))
+			{ // Don't missile self -- [MK] unless explicitly allowed
 				return true;
 			}
 

src/scripting/thingdef_data.cpp

@@ -318,6 +318,7 @@ static FFlagDef ActorFlagDefs[]=
 	DEFINE_FLAG(MF8, FRIGHTENING, AActor, flags8),
 	DEFINE_FLAG(MF8, BLOCKASPLAYER, AActor, flags8),
 	DEFINE_FLAG(MF8, DONTFACETALKER, AActor, flags8),
+	DEFINE_FLAG(MF8, HITOWNER, AActor, flags8),
 
 	// Effect flags
 	DEFINE_FLAG(FX, VISIBILITYPULSE, AActor, effects),