Enhancement: Add the ability to Receive Renard Protocol in addition to transmit

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Currently the Renard driver can only Transmit, it would be nice if it also was 
able to receive. When the object is called the mode of operation should be 
specified, Tx or Rx. 

Note: To do this the enable pin on the transceiver must be controlled since it 
determines the data direction of the transceiver. Enable Low = Rx, Enable High 
= Tx.

Original issue reported on code.google.com by b...@byaroch.com on 3 Jun 2011 at 6:25