fixed some issues with reviving monsters

- fixed: Thing_Raise didn't properly set the spawn health.
- fixed: Thing_Raise did not the CanRaise state flag.
- fixed: Reviving a monster must also reset the damage type.
- fixed: Thing_Raise reset the actor after calling the raise state, but it should be before, just as the Archvile code is doing.
- consolidated some common code of Thing_Raise and Archvile resurrection into AActor methods.

src/p_mobj.cpp

@@ -6074,6 +6074,49 @@ int AActor::SpawnHealth()
 	}
 }
 
+FState *AActor::GetRaiseState()
+{
+	if (!(flags & MF_CORPSE))
+	{
+		return NULL;	// not a monster
+	}
+
+	if (tics != -1 && // not lying still yet
+		state->GetCanRaise()) // or not ready to be raised yet
+	{
+		return NULL;
+	}
+
+	if (IsKindOf(RUNTIME_CLASS(APlayerPawn)))
+	{
+		return NULL;	// do not resurrect players
+	}
+
+	return FindState(NAME_Raise);
+}
+
+void AActor::Revive()
+{
+	AActor *info = GetDefault();
+	flags = info->flags;
+	flags2 = info->flags2;
+	flags3 = info->flags3;
+	flags4 = info->flags4;
+	flags5 = info->flags5;
+	flags6 = info->flags6;
+	flags7 = info->flags7;
+	DamageType = info->DamageType;
+	health = SpawnHealth();
+	target = NULL;
+	lastenemy = NULL;
+
+	// [RH] If it's a monster, it gets to count as another kill
+	if (CountsAsKill())
+	{
+		level.total_monsters++;
+	}
+}
+
 FDropItem *AActor::GetDropItems()
 {
 	unsigned int index = GetClass()->Meta.GetMetaInt (ACMETA_DropItems) - 1;