* Added '--bitrate=', '--channels=', '--format=', '--quality='
and '--samplerate=' to rdexport(1) in 'utils/rdexport/rdexport.cpp'
and 'utils/rdexport/rdexport.h'.
* Documented the '--allow-clobber' switch in
'docs/docbook/rdexport.xml'.
* Documented the '--continue-after-error' switch in
'docs/docbook/rdexport.xml'.