Adds slot machines.

What it says on the tin.
It works with coins and shit.

emagging it is top lyl and shoots the coins at you.

Probabilities and values are currently completely arbitrary, feel free to suggest changes.

This does not place them on the map.

![slotmachinebetter gif](https://cloud.githubusercontent.com/assets/3975713/3461118/cb52ef82-021e-11e4-989f-6e41d5040275.gif)

You can add the throw argument to the coin_give proc and then pass it along to the dispense proc.