Finish the input mapping

[jamestmartin]

There are some desirable features we could have during TeleOp. We would like to

• Take references to input variables rather than copying their values
• Rename buttons based on what they do rather than their position on the gamepad
• Associate behaviors with buttons (event listening) rather than scattering input reading throughout the codebase
• Produce buttons with combined behaviors and treating them as a unit (e.g. if x is arm up and y is arm down, we can combine these into a ButtonPair(x, y) and assign the arm behavior as a produced direction sign. This sounds complicated, but a demonstration would show that it isn't.

Since most behavior in TeleOp is based on input, I suspect this will drastically improve the codebase.