Turing Pi 2 layer for stacking mini-ITX case

This is a remix of lightofhonor's excellent stacking Mini-ITX case design to add a motherboard module more suited to the Turing Pi 2.

NOTE: The "nodes" stand up higher than the walls of this module! You can generally stack TP2 layers on top of one another, but putting anything else above this module (like a lid) will **very likely require you print the 10mm spacer.**

Update (2024-12-02): It **is** supposed to be 6.2". The diagram I saw that referenced 6.25" was wrong. Reverted back to V3. I deleted the V4 version.

~~Update (V4, 2024-11-26):~~
- ~~Augh! I had the horizontal pitch of the mounting screw holes wrong. Corrected: 6.2" -> 6.25"~~
- ~~Deleted files for V1-3~~

Update (V3, 2023-06-02):
- Power hole expanded (8mm->8.5mm diameter)
- Power hole moved 0.5mm inward
- Hexagonal pocket (2mm deep, 10.25mm AF) added around power hole to hold PSU barrel jack hexnut
- Rear I/O aperture area keepout reduced (2.54mm -> 2.04mm) to make room for all this

Update (V2, 2023-04-30):
- microSD