Support more than one 32 bit value to be sent. Added whitening algorithm.

The RcSwitchTransmitter may be use to transmit a bigger data packet (more than the typical 24 bits that an RC typically sends). That can now be done by sending more bits that must be stored in an array of uint32_t values. For bigger data packets, a whitening algorithm shall be used. A whitening algorithm has been added to the API. The bigger data packets can be received by the RcSwitchReceiver from version v0.8.0 onwards.