Converted assembled balloon to blender format. Added render of assembled balloon

Added mounts for feather components. Added feather models for printing. Refactored feather software.

- Basics of soft spi

+ Added attiny2313a datasheet

Prepared Keel PCB for print

- Updated Keel PCB

+ Added scripts for uploading firmware

* Fixed Feather

- [Feather] Updated script and fixed USI byte overflow

- [Feather] New test version of package processing (working but poorly)