Update documentaion and changelog with respect to software mixing and playbin2 switch.

docs/changes.rst

@@ -23,7 +23,7 @@ v0.8 (in development)
   mixer that will work on your system. If this picks the wrong mixer you can of
   course override it. Setting the mixer to :class:`None` is also supported. MPD
   protocol support for volume has also been updated to return -1 when we have
-  no mixer set.
+  no mixer set. ``software`` can be used to force software mixing.
 
 - Removed the Denon hardware mixer, as it is not maintained.
 
@@ -73,6 +73,9 @@ v0.8 (in development)
   ``$XDG_MUSIC_DIR`` substitution. Defaults for such settings have been updated
   to use this instead of hidden away defaults.
 
+- Playback is no done using ``playbin2`` from GStreamer instead of rolling our
+  own. This is the first step towards resolving :issue:`171`.
+
 **Bug fixes**
 
 - :issue:`72`: Created a Spotify track proxy that will switch to using loaded
@@ -96,6 +99,8 @@ v0.8 (in development)
 - Fixed incorrect track URIs generated by M3U playlist parsing code. Generated
   tracks are now relative to ``LOCAL_MUSIC_PATH``.
 
+- :issue:`203`: Re-add support for software mixing.
+
 
 v0.7.3 (2012-08-11)
 ===================

mopidy/settings.py

@@ -111,7 +111,8 @@ LOCAL_TAG_CACHE_FILE = u'$XDG_DATA_DIR/mopidy/tag_cache'
 #: Expects a GStreamer mixer to use, typical values are:
 #: ``alsamixer``, ``pulsemixer``, ``ossmixer``, and ``oss4mixer``.
 #:
-#: Setting this to :class:`None` turns off volume control.
+#: Setting this to :class:`None` turns off volume control. ``software``
+#: can be used to force software mixing in the application.
 #:
 #: Default::
 #: