- fix license for printf.c (take from newlib instead of glibc)

- fix license for start.S (find a BSD version)

- openocd flashing
  use run_algorithm to hook ROM NVM functions
  see flash/stm32x.c

- add timestamp to received packets 

- add a way to set modes: tx_only, rx_only, txrx. (so you can be lazy
  and have blocks of code that don't need to handle rx packets)

- beacon sync

- CCA and ED.

- auto-acking and ack managment
  keep a set of bit fields, one bit per sequence number (DSN), so 32 bytes
   total.
  Set them all to 1 initially. When a DSN is sent, clear the bit. Set
   the bit when the ack is received.
  Do anything special with sent but unacked packets? Maybe, so you can
   retransmit them.