Never call mapShutdown() or environReset() in mid-missions, since we come back

to the main map, and that data must be valid or we get no textures, and the water
heights will be incorrect.
Also complain loudly if the mission type is wrong (should never happen!)

fixes ticket:2262
(cherry picked from commit b859c3d6997a9860662b1be8753c643fc48f2a72)

src/mission.c

@@ -852,9 +852,8 @@ void restoreMissionData(void)
 	gwShutDown();
 	if (game.type != CAMPAIGN)
 	{
-		// we don't want this to happen on missions
-		ASSERT(false, "mapShutDown() is being called");
-		mapShutdown();
+		ASSERT(false, "game type isn't campaign, but we are in a campaign game!");
+		game.type = CAMPAIGN;	// fix the issue, since it is obviously a bug
 	}
 	//restore the game pointers
 	for (inc = 0; inc < MAX_PLAYERS; inc++)
@@ -916,9 +915,6 @@ void restoreMissionData(void)
 
 	resetRadarRedraw();
 
-	// reset the environ map back to the homebase settings
-	environReset();
-
 	//intSetMapPos(mission.playerX, mission.playerY);
 }