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)

slots-on is the state for when it's spinning, not for when it has power. There are no unpowered sprites. I cannot change this since the sprites are not mine.