Ports

"permissive" is a flag on the command line to turn on the permissive mode. Ignoring errors is convenient with applications that fail on the configuration of some serial port features not yet supported. These features might not be eventually used or required. For instance while not being able to increase the size of the i/o buffers, the application might not work optimally but still.

Also fixed set_baud_rate()/get_baud_rate() in comm_serial_sys.c (the comm_sercx_sys.c's implementation were used by default. comm_sercx2_sys.c, comm_sercx_sys.c and comm_serial_sys.c now use the same implementation)

If at some point all features will be supported, the permissive mode should be removed and comm_*_sys.c files likely merge in a single one.