Original commit message from CVS:

* docs/plugins/Makefile.am:
* docs/plugins/gst-plugins-base-plugins-docs.sgml:
* docs/plugins/gst-plugins-base-plugins-sections.txt:
* gst/volume/gstvolume.c:
add/fix docs
* gst-libs/gst/audio/audio.c: (gst_audio_frame_byte_size):
* gst-libs/gst/audio/audio.h:
add conversion macros for frames <-> clocktime