Added initial version of audioconvert, a generic converter of integer audio/raw formats.

Original commit message from CVS:
Added initial version of audioconvert, a generic converter of integer audio/raw formats.
It currently supports conversion of
- channels (mono/stereo only, until someone tells me how to mix other channels)
- endianness (little/bi endian)
- signedness
- width (8, 1, 24 and 32 bits)
- depth (1 - width bits)
missing:
- enough testing (I intend to write a testsuite for this, but that's pending)
- samplerate conversion
- other goodies like format conversion etc
Expect bugs when using it.

problems this should solve:
- encoding wav files on big endian machines
- goom working with mono audio files in gst-player
- Iain's soundcard (that one is a problem in itself)
- complaints about missing conversion
- too many age old, nearly unmaintained plugins (stereo2mono etc.)
Have fun.

configure.ac

@@ -232,7 +232,7 @@ AC_SUBST(GST_PLUGIN_LDFLAGS)
 
 dnl these are all the gst plug-ins, compilable without additional libs
 GST_PLUGINS_ALL="\
-        ac3parse adder audioscale auparse avi asfdemux cdxaparse chart\
+        ac3parse adder audioscale auparse avi asfdemux audioconvert cdxaparse chart\
         cutter deinterlace effectv festival filter flx goom\
         intfloat law level\
         median mixmatrix mpeg1enc mpeg1sys mpeg1videoparse mpeg2enc mpeg2sub\
@@ -1049,6 +1049,7 @@ gst-plugins.spec
 gst/Makefile
 gst/ac3parse/Makefile
 gst/adder/Makefile
+gst/audioconvert/Makefile
 gst/audioscale/Makefile
 gst/auparse/Makefile
 gst/avi/Makefile