[communication] Modifies the way UART is hadled by Xbee a,d superbus, creates a new library to make the UART "frame oriented". WARNING : nothing is tested yet. WARNING II : linux and LPC compatibilities are to be made.
* Creates a core "timeout" library for arduino (TODO for linux and LPC).
* Renames some #define and adds one parameter (rst pin) in node_cfg.h
* Creates the UART "framing" library (sends and receives frames over UART with the same constraints as Xbee API mode 2). files lib_UART_framing.[c,h].
* Creates the appropriate drivers for arduino in lib_UART_framing_arduin_drivers.[c,h].
* Creates the UART4sb.h file.
* Renames Xbee_api function (to be consistent with the rest).
* Modifies Xbee_api functions and drivers to use the newly created UART_framing lib.
* Modifies the Xbee4sb.[c,h] files.