- Remove the propsprivate header file

- Remove the propsprivate header file

Original commit message from CVS:
- Remove the propsprivate header file
- Added new API for properties.
- Moved the clock distribution to the scheduler.
- Removed the lock from GstCaps
- Added boxed types for Caps/Props
- Simplified the clock, new systemclock implementation
- Removed deprecated element_info/send_event functions
- First step at exposing more info in the pad_connect functions
- Queue cleanup
- Make the scheduler aware of other schedulers inside it
- Added the _SELF_SCHEDULABLE flag to gstthread
- Removed _get_widget from _utils, changed to new props API
- Make fakesink sync on timestamps when requested
- Removed the offset notify from filesrc
- Added a fast scheduler
- some scheduler cleanups.