- scriptified Heretic's mace.

- fixed: FxAssignSelf did not the correct number of registers for vector operations.
- fixed a few asserts in vector2 instructions.
- turned the virtual AActor::HitFloor method into a flag MF7_SMASHABLE. The only use of this function was to kill Hexen's pottery when they hit the floor, and this looks like something that can be exposed to modders less clumsily.

src/scripting/thingdef_data.cpp

@@ -294,6 +294,7 @@ static FFlagDef ActorFlagDefs[]=
 	DEFINE_FLAG(MF7, USEKILLSCRIPTS, AActor, flags7),
 	DEFINE_FLAG(MF7, NOKILLSCRIPTS, AActor, flags7),
 	DEFINE_FLAG(MF7, SPRITEANGLE, AActor, flags7),
+	DEFINE_FLAG(MF7, SMASHABLE, AActor, flags7),
 
 	// Effect flags
 	DEFINE_FLAG(FX, VISIBILITYPULSE, AActor, effects),