[hpsdr] multiple rx

[alex]

Clarification - i did not say that having several mercury's for phasing 
or h/v polarization, i was talking about having more than, say 2, 
demod-able receiver chains in the fpga so having more than 2 bands 
simultaneously receiving, of course this doesn't stop having several 
modes because it would still have 192khz to play with.

Ok in some (very rare circumstances) there might be reason to have many 
bands but surely the large extra cost to everyone would make it not 
worth while integrating this into every normal mercury.