[FIXED][BUG][PLAYER] All Lemmings go into a teleporter with no reciever -> crash

[IchoTolot]

This is quite a special case which I encountered while building a level with a low lemming count and having a teleporter without it's reciever yet.

Reproduce:

- Make a level with preferrably a low Lemming count and let every "not dead" Lemming walk into a telepoter with no reciever

This will cause an "Index list out of bounds" exception and I had to close NL via the windows task manager.

A simple fade out of the level into the result screen would be a better thing here

[Nepster]

The behavior in V1.43 was: Lemmings do never even enter teleporters without receivers, i.e. teleporters without receivers act as no-effect objects. As far as I know this is still the intended behavior.

[Nepster]

I restored now the V1.43 behavior to ignore teleporters without receivers. If you (i.e. any forum member, not only IchoTolot) prefer a different behavior, e.g. that such teleporters behave like triggered traps, then please reply here or start a separate discussion thread.

Moreover I found and fixed a related bug: NL crashed as well when hovering over a disabled teleporter or receiver when in clear-physics mode.