Enhanced the documentation.
Added radio parameter RADIO_PARAM_CCA_THRESHOLD for STM32W
Added radio parameters RADIO_PARAM_RSSI and RADIO_PARAM_TXPOWER for cc2420
Split the radio parameter ADDRESS_HANDLER into RX_MODE and TX_MODE.
Implemented radio rx mode parameter for STM32W
Changed project configuration from CSMA to nullmac in er-rest-example to reduce code size - this allows the example to compile again on Tmote Sky.