Original commit message from CVS:
* docs/design/draft-push-pull.txt:
* docs/design/part-events.txt:
* docs/design/part-overview.txt:
* docs/design/part-scheduling.txt:
Replace all _pull_region() with _pull_range()
Original commit message from CVS:
Added state change code.
Added/updated docs.
Added sink base class, make fakesink extend the base class.
Small cleanups in GstPipeline.