Deleted shared_usb.h because it was a copy of shared_dict_usb.h
This build_stm .hex does include some NROM flash updates to allow
checking if the last byte programmed successfully because was having
weird problems with that. But not ready to commit all those changes and
they're highly unrelated to this commit.
Now that usb code doesn't use any .data nor .bss need to fully separate
the USB firmware code from the application. Main way to do this will be
to have usb code be effectively entirely interrupt driven.
Thinking the best way to initialize usb will to have the application
code jump to the USB ISR and maybe use some messaging system with the 2
unused usb_buff indexes (4Bytes).
The USB code will include the vector table, so it will point to the
reset handler, but that will point to the application code's reset
handler, just need to make sure that's at a fixed location.
The USB code is just over 1KByte last I checked, so dedicating 2KByte
should be good. Erase granularity is 1 page (1KB on C6, 2KB on RB). So
that will work well. Write protection granularity is 4KByte, but really
we shouldn't need to use write protection as there will always be the
built in bootloader to save a bricked device.