ordinary mixer:
- revised Ordinary Mixer I/O type
- sndo_mixer_open() take PCMs rather than strings to pass
the real relationship
- an initial version of toplevel alisp script
more alisp development:
- renamed a* functions to A* functions (acall -> Acall etc.)
- many improvements (unset*, exfun, Acall pcm_info, Asnderr, Asyserr)