MainBoard: Fix microUSB pinout, add some tSilk

MainBoardSCH: Reorder sheets and renumber parts

MainBoardBRD: Add isolation cutout polygon around analog ground vias

MainBoardBRD: Fix DRC errors

MainBoard: Fix USB connectors, ROUTED

MainBoard: Routing (coprocessor power), remove one output capacitor from LDO - shared with STM

MainBoard: Mirror iLed step-down (to the bottom side)

MainBoard: Mirror motor connectors (to the bottom side) and swap signals to keep previous routing

MainBoard: Compete USB, swap VUSB_DET and BUTTON_ON, all parts on board

MainBoard: Fix USB connectors packages, add Design block backup file extensions to gitignore