Add some maphack that're specific to coop.

These are some corner cases that can only happen when one or both
players die at the wrong place and time. This is based upon a fix by
Maraakate. This fixes issue #9.

src/g_spawn.c

@@ -283,6 +283,35 @@ spawn_t spawns[] = {
 	{NULL, NULL}
 };
 
+qboolean Spawn_CheckCoop_MapHacks (edict_t *ent)
+{
+	if(!coop->value || !ent)
+	{
+		return false;
+	}
+
+	if(!Q_stricmp(level.mapname, "xsewer1"))
+	{
+		if(ent->classname && !Q_stricmp(ent->classname, "trigger_relay") && ent->target && !Q_stricmp(ent->target, "t3") && ent->targetname && !Q_stricmp(ent->targetname, "t2"))
+		{
+			return true;
+		}
+		if(ent->classname && !Q_stricmp(ent->classname, "func_button") && ent->target && !Q_stricmp(ent->target, "t16") && ent->model && !Q_stricmp(ent->model, "*71"))
+		{
+			ent->message = "Overflow valve maintenance\nhatch A opened.";
+			return false;
+		}
+
+		if(ent->classname && !Q_stricmp(ent->classname, "trigger_once") && ent->model && !Q_stricmp(ent->model, "*3"))
+		{
+			ent->message = "Overflow valve maintenance\nhatch B opened.";
+			return false;
+		}
+	}
+
+	return false;
+}
+
 /*
  * Finds the spawn function for
  * the entity and calls it
@@ -688,14 +717,14 @@ SpawnEntities(const char *mapname, char *entities, const char *spawnpoint)
 			}
 			else
 			{
-				if (
+				if (Spawn_CheckCoop_MapHacks(ent) || (
 					((skill->value == 0) &&
 					 (ent->spawnflags & SPAWNFLAG_NOT_EASY)) ||
 					((skill->value == 1) &&
 					 (ent->spawnflags & SPAWNFLAG_NOT_MEDIUM)) ||
 					(((skill->value == 2) ||
 					  (skill->value == 3)) &&
-					 (ent->spawnflags & SPAWNFLAG_NOT_HARD))
+					 (ent->spawnflags & SPAWNFLAG_NOT_HARD)))
 					)
 				{
 					G_FreeEdict(ent);