MIDI filter

This is a compact enclosure for a MIDI filter. It has a Din-5 MIDI "in" and "out" connector on either side. The MIDI signal is filtered by a [Teensy LC](https://www.pjrc.com/teensy/teensyLC.html) microcontroller board.

*Note: I was hoping that the 5V from the MIDI was enough to power the teensy, but the output impedance of my Arturia Keystep is too high and the voltage drop to large to power the board. Hence I will be designing a variant of this, which also exposes the micro-USB connector of the Teensy to power it.*