Disable nocollisionat() for conveyors

While my previous commit fixes the glitchy y-position when you get stuck
inside a conveyor, I noticed that getting inside a conveyor seems to
always push the player out, despite conveyors sharing the same code with
moving platforms, which has code to temporarily disable their own
collision when the player gets stuck inside them, so that the player
DOESN'T get pushed out.

Well, it turns out that the reason this happens is because conveyors in
a room that get placed during mapclass::loadlevel() get tile 1 placed
underneath them. This is mostly so moving platforms will collide with
them, because otherwise platforms don't collide with other platforms,
and a conveyor is considered a platform.

This means that a conveyor without any tiles behind it will simply get
the player stuck if they get inside it, and the player won't be pushed
out. This is bad, because conveyors don't move, so they'll be stuck
there forever until they press R (or save, quit, and load). This
situation doesn't come up in the main game, but it COULD come up in
custom levels that use the internal createentity() command to create
conveyors that don't have any tiles behind them.

It seems good to fix this as well, while we're at it fixing conveyor
physics, so I'm fixing this as well.

desktop_version/src/Entity.cpp

@@ -4674,6 +4674,11 @@ void entityclass::collisioncheck(int i, int j, bool scm /*= false*/)
         }
         break;
     case 2:   //Moving platforms
+        if (entities[j].behave >= 8 || entities[j].behave < 10)
+        {
+            //We don't want conveyors, moving platforms only
+            break;
+        }
         if (entitycollide(i, j))
         {
             //Disable collision temporarily so we don't push the person out!