- exported all necessary functions to create a mixer module outside alsa-lib
- separated simple mixer API from the simple mixer implementation
(using callbacks as usuall)
- src/mixer/simple.c is the core
- src/mixer/simple_none.c is the current (no-abstraction) implementation
based on control names; note that this module does not depend on
internal ALSA structures now
- src/mixer/simple_abst.c is the ongoing abstraction which will use
external dynamic modules; src/conf/smixer.conf will describe which
modules will be used depending on the components from the driver
