Sparkfun ESP32 Thing case

This is a work-in-progress case for the great *ESP32 Thing* from *Sparkfun*. I love this board: it has everything for development and testing of the ESP32.

This is my first 3D design, so it comes with quite some room for improvements:
- my board is currently header-less. I provisioned some room for headers below the board, but it would need another cover
- speaking about the cover, some holes for LED/headers/buttons would be great, but would make it either very big, or fragile...
- the box is a little bit too tight, it was difficult to insert the board, and would be even more to remove it
- the small part between USB and battery connectors is to thin, and broke right away; I should remove it