Project Predator: Nerf Stryfe mod

See [hivemonkey.com](https://hivemonkey.com/project-predator-part-one) for the full project writeup, including electronics, code, Stryfe modifications, etc.

This is a case specifically designed to fit on the left side of a Nerf Stryfe and mount a particular homebrew electronics package, consisting of a Raspberry Pi Zero fitted with a Pimoroni Rainbow Hat and an ultrasonic rangefinder. The LEDs, alphanumeric display, and capacitive buttons are all available from the back of the case while the rangefinder looks forward to, well, find range. A slot on the right side of the case admits wires, since power, magazine sensing switch, and trigger switch are all located inside the body of the Stryfe.

The Rainbow Hat displays shots remaining in the magazine using the colored LEDs across the top, and displays range to target (in cm) in on the alphanumeric display. It also buzzes to let you know when the mag is either empty, or removed. The buttons on the bottom of the Hat adjust possible