Add climber

[lindsayvallen]

Add software support for climber that consists of two talons controlling two motors for a winch.

• Add basic throttle manual control
• Add full control options similar to elevator
• Incorporate limit switch (if that hardware added)

[lindsayvallen]

First pass at basic throttle manual control by updating feature/climber_addition commit c421a25. Throttle set at +/- 0.8 using driver dpad. Not yet tested.

[lindsayvallen]

Done adding speed control and position hold; located on weapons left stick. No limit switch or homing switch (at least as of yet), and not making set point buttons (like elevator) because not needed. Merged into master as of commit 100f79d.