[Discuss-gnuradio] Announcement: GRC USRP2 support and improved USRP stuff

[Josh Blum]

--USRP2--
USRP2 source and sinks blocks are now available in GRC. The GRC blocks 
reflect the current USRP2 API in the trunk. Therefore, not all 
daughterboard options are available at this time.

--USRP--
The simple and dual usrp source and sink blocks have been polished. The 
mux parameter has been removed and the subdevice parameter has been 
replaced with antenna selection (RXA, RXB, TX/RX, RX2). Configuration of 
the mux and subdevice occurs internally in the simple usrp wrapper 
classes. Also, the dual usrp source has complete options for all 
possible combinations of RX antennas.

There could be bugs. Enjoy!

-Josh