Minor PVQ cleanup
Rewrote od_convert_block_down to handle edge cases.

Exposed od_convert_block_down in tf.h for use in 4x4 TF intra
 prediction patch.
Merge branch 'master' of git://git.xiph.org/daala
Fix a few typos in design doc and source comments

Signed-off-by: Nathan E. Egge <negge@dgql.org>
Reformatting the source code.

Signed-off-by: Jean-Marc Valin <jmvalin@jmvalin.ca>
Reformatting pvq.c
Signed-off-by: Jean-Marc Valin <jmvalin@jmvalin.ca>