Merged eb/u2-mimo-wip -r10297:10317 into the trunk. This contains
down and dirty test code that confirms that we can coherently transmit
different signals to two USRP2s connected via a mimo cable.
app_common_v2.h and app_passthru_v2.h were slightly modified, but
these changes to not alter the behavior of the standard code (txrx).
git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@10318 221aa14e-8319-0410-a670-987f0aec2ac5