libcdaudio.so enhancement

CD Audio Plugin v1.2.7 (libcdaudio.so)

I use Solaris 8 (intel) and it is possible to listen to the CD output thru
the sound device.  However you cannot control the volume of the CD playback
using XMMS and I can only do this by using the CD player volume control or
another application.

I have modified this Input plugin to have an additional configurable option
which allows the playback volume to be controlled by the Output plugin (in
my case libsolaris.so) if required.  This allows me to adjust the CD
playback volume by using the XMMS UI volume slider.

I feel that this is a useful enhancement,  but as a newcomer to this project
I am unaware of how I could submit my code changes for review and possible
inclusion in the next release.

David A. Harris