usb: simplify descriptor definition
usb: keep track of function iface and ep offset
usb: pass correct transfer length in tx callback
vusb: more debugging output
vusb: implement URB unlinking
usb: add cdc-acm
schematic: don't use identifiers in comment

They just change under us and become stale.
hardware/Makefile: kicad schematic plots changed name
fab outputs from 87e118d hardware/Makefile: kicad schematic plots changed name