Add ability to set soundcard for Radio1 and Radio2 for DVK

[ny4i]

From Terry, N4TZ:

I use the TR4W DVK a lot. But, it relies upon external switching of the transmit stream (I have used the DXDoubler successfully).

With most recent rigs having internal USB soundcards, this is a problem. I need a way to tell TR4W to use Soundcard A for rig A and Soundcard B for rig B.

Any hope?

Terry N4TZ