[chibios] Add support for a full ChibiOS arch
This is replacing the previous mix chibios/libopencm3:
- all drivers are ported to the new arch
- it was hard to go forward and take advantages of the RTOS, now it is much easier
- switch to v3 of ChibiOS
- for now, it is functionaly the same than before
- the previous variable length array mechanism used internaly by the
sdlog is replaced by a more efficient library called TLSF (allow
constant time malloc/free)
Only the realtime scheduler and SDIO driver from ChibiOS is used.
This brings the support of the SD log on Apogee boards. The current
solution is not fully satisfactory and is an intermediate solution
before switching to a 'pure' ChibiOS arch.
Some of the implementations can be cleaned and/or improved, but since it
is not a long term solution, I doubt it is worth the effort here.
Normal bare-metal libopencm3 code is of course still working.
Git submodules:
- chibios: 2.6.2
- fatfs: patched version for chibios+pprz
