big simple mixer update

- 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

src/mixer/mixer_simple.h

@@ -0,0 +1,25 @@
+/*
+ *  Mixer Simple Interface - local header file
+ *  Copyright (c) 2005 by Jaroslav Kysela <perex@suse.cz>
+ *
+ *
+ *   This library is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU Lesser General Public License as
+ *   published by the Free Software Foundation; either version 2.1 of
+ *   the License, or (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU Lesser General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Lesser General Public
+ *   License along with this library; if not, write to the Free Software
+ *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ */
+
+#include "mixer_abst.h"
+
+int snd_mixer_simple_none_register(snd_mixer_t *mixer, struct snd_mixer_selem_regopt *options, snd_mixer_class_t **classp);
+int snd_mixer_simple_basic_register(snd_mixer_t *mixer, struct snd_mixer_selem_regopt *options, snd_mixer_class_t **classp);