Add defines for data and lock safe methods in radioSendData
Standardize exit codes for radioSendData according to stdlib.h
Merge branch 'master' into cmd_default
UART driver added with the hope of putting received packets direcly in the command queue, and just accepting outgoing packets one at a time. Doesn't seem to work with transmission currently.
UART driver works with arbitrary callback function for RX
Merge branch 'master' into cmd_default