Escape 106 can tp in invalid posiuiton when custom door are use

[warquys]

106 escape use doors to tp the player.

A patch on Scp106PocketExitFinder.ValidateDoor is required to avoid Tp the player on custom door. Some custom door are placed on wall (to signal a TP) lead to create a pocket exit for 106. When the player exit 106 pocket it may be Tp in void.