PipeWire 0.2.3

- Fix deviceprovider caps introspection
- Refcounting fixes in pipewiresrc
- Remove clock interpolation from stream
- Improve clock in gstreamer elements
- Remove spalib
- Fix crash with pw_map
- Add version number to hook list
- Improve driver mode in gstreamer elements
- add daemon options
- add man pages

Work is ongoing in the work branch that features a completely new
scheduling method that will enable audio support. Some of these
API changes are backported in this branch.