Log Message:
Changes 1.2.1:
* Various build updates (see SVN)
* Add ogg_stream_pageout_fill() to API to allow applications
  greater explicit flexibility in page sizing.
* Documentation updates including multiplexing description,
  terminology and API (incl. ogg_packet_clear(),
  ogg_stream_pageout_fill())
* Correct possible buffer overwrite in stream encoding on 32 bit
  when a single packet exceed 250MB.
* Correct read-buffer overrun [without side effects] under
  similar circumstances.
* Update unit testing to work properly with new page spill
  heuristic.