Log Message:
Changes 1.3.2:
* vorbis: additional proofing against invalid/malicious
  streams in floor, residue, and bos/eos packet trimming
  code (see SVN for details).
* vorbis: Added programming documentation tree for the
  low-level calls
* vorbisfile: Correct handling of serial numbers array
  element [0] on non-seekable streams
* vorbisenc: Back out an [old] AoTuV HF weighting that was
  first enabled in 1.3.0; there are a few samples where I
  really don't like the effect it causes.
* vorbis: return correct timestamp for granule positions
  with high bit set.
* vorbisfile: the [undocumented] half-rate decode api made no
  attempt to keep the pcm offset tracking consistent in seeks.
  Fix and add a testing mode to seeking_example.c to torture
  test seeking in halfrate mode.  Also remove requirement that
  halfrate mode only work with seekable files.
* vorbisfile:  Fix a chaining bug in raw_seeks where seeking
  out of the current link would fail due to not
  reinitializing the decode machinery.
* vorbisfile: improve seeking strategy. Reduces the
  necessary number of seek callbacks in an open or seek
  operation by well over 2/3.