AntiCheat: Prevent players from wallhacking through cave entrance

This is a manual coded check which prevent players from wallhacking through the cave entrance.

Luckily there is no place on the map which is left to the entrance and which must be walkable while it is closed.
So a simple check whether a movement crosses a given vertical line from east to west, while the entrance is closed, is sufficient to prevent players from hacking through it..

Tested on a collision-disabled client, tested blink. Works for me..
Let me know :)