This is an attempt at not segfaulting on errors but reporting some usefull info instead.

This is an attempt at not segfaulting on errors but reporting some usefull info instead.

Original commit message from CVS:
This is an attempt at not segfaulting on errors but reporting some
usefull info instead.
- bin changes so errors can propagate.
- changed the _FAST macros to _CAST because that is what they do.
- removed all references to cothreads out of the core, they are
really a scheduler issue, handler with a sched_private gpointer.
- added a live buffer count, for debugging buffer leaks.
- added error checking in gst_scheduler_state_transition this solves the
"out of cothreads" problem.
- GST_ELEMENT_NO_ENTRY == GST_ELEMENT_INFINITE_LOOP
- added 2 private element flasg for use by the scheduler
(_COTHREAD_STOPPING) is now
- added scheduler entry points:
- _yield : to create possible scheduling points.
- _interrupt: to stop execution of an element.
- _error: to signal en error condition to the scheduler.
- improved error messages for pads.
- signal gst_element_error where appropriate.
- added the a new bin to the parent before entering it so one can reference
its children.
- queue memleak fixes on dispose.
- added possible deadlock detection in queue (turned off be default)
- GstBasicScheduler is a real class of its own now, hiding its internal
variables.
- GST_ELEMENT_IS_COTHREAD_STOPPING is gone. either call explicit _yield
operations, or make a sane loop.
- Better state change handling in filesrc. Better error reporting/recovery
too.
- updated core plugins.
- detect non decoupled elements on scheduler boundries and error.