- Moved all modified sprites to modular_citadel, made overrides for sec-tread and eng-tread, reverted original robots.dmi
- Added open cover states to modular_citadel robots.dmi
- Removed light found on normal engi-borg sprite that was not on the tread version.
- Adds the mining droid sprite to the default mining borg module selection.
- Adds movement states for both security and engineering tank tread sprites.
- Fixed static security tread state sprite.
