redesign shifter paddles to use the magnets as buttons

[rickyelopez]

Instead of having the shifter paddle press down on a little button, attach some wires to the magnets on the paddle and on the paddle base. Then, when the magnets are separated the circuit will be broken, which we can measure! Use that event to trigger shifts.

This change should mean that the entire shifter package can be made more compact and much simpler. Plus, assembly will be easier.

• Add channels for wires to pass through to get to magnets
• Figure out how to securely connect wires to magents - can we solder? Might break magnets
• Test changes