API docs. revived _buffer_ref_by_count fast types for scheduler and bin.

API docs. revived _buffer_ref_by_count fast types for scheduler and bin.

Original commit message from CVS:
API docs.
revived _buffer_ref_by_count
fast types for scheduler and bin.
error checking on plugin features;
removed some prototypes that were not implemented (gst_pipeline_iterate
comes to mind)
remove gst_pad_event until we know what it's supposed to do.
remove sinesrc, it wasn't compiles anymore, so...
updates to various elements that used the old event API.