Release v0.22

v0.22
=====

- improve inverted cursor support
- use system-wide trust certificate store
- make sasl support work with other method than MD5
- fix some clipboard crasher, limit clipboard size
- fix various regressions:
  usbredir, alt-tab on win32, palette crash, agent notification, old
  protocol support, sasl ending crash, gthread coroutine crash, close
  sockets on migration, pulse backend crash
- fix a few memory leaks
- build-sys improvements