[CM] sndlib ESD support

[Bill Schottstaedt]

It appears that the Enlightened Sound Daemon is no longer
supported.  Would it be a problem if I remove support for it
from sndlib?  How about OSS?  Sun?  HPUX?

Also, in the 10 or 20 years since the audio stuff was first
implemented, audio hardware, and OS support of it, has
changed a lot.  I'd like to remove all the input functions,
and the hardware state descriptors, and change the output
functions to be purely callback-driven.  So, 95% of audio.c
would go away, along with rtio.scm, play.scm, oscope.scm,
and various other such stuff.  How important is audio
input to anyone (in Snd, or CLM)?