Yet another renaming of some mixer methods:

devices(), stereodevices(), recdevices() ->
  controls(), stereocontrols(), reccontrols()

Based on recommendation of Hannu Savolainen <hannu@opensound.com>:

  The right term to use for things like bass/treble/mic/vol/etc is
  "control".

  "Device" refers to different mixer devices (/dev/mixer0 to /dev/mixerN).

  "Channel" cannot be used because it refers to mono/stereo/multich
  channels. In fact most mixer controls have left/right channels so ...