Logitech G920 Shift Firmness Mod

Heavily inspired by [this design for the Logitech G27](https://www.thingiverse.com/thing:2284348)

Download the source here: http://a360.co/2zuTF5n

Still needing several tweaks to reduce friction and squeakiness (particularly the shifter failing to return to center before the plastic has worn in), and documentation on how to set it up. However even with this unfinished mod it's still miles better than the looseness of the stock design.