Bukkit

Fixes a NPE that pops up with some spigot servers

* Note on the shooting arrow on button breaks Lift bug: From what I have read there is no way to check the block an arrow hits without breaking support for other bukkit servers like Spigot (if you do know of a plugin tell me. I want to check their code). The three options are to break spigot support, remove wood buttons, or disable arrows.
* I have not tested minecarts with plugins that modify minecart behavior, like minecart mania. Your mileage may vary.
* I have done some testing with the minecarts, but not a lot. Let me know if there is some unwanted behavior. Also note that if the minecart is going too fast it might bounce on a wall or go through the lift before the lift can be triggered.