Mir 0.9.0

- Enhancements:
  . New simpler API to configure and run a mir server.
  . The event loop is now based on GLib's main loop library instead of
    Boost.Asio.
  . For Android platforms, the server now sends buffer fence fds to its
    clients instead of potentially stalling the compositor thread waiting
    for them to be signalled.
  . New client debug interface to translate from surface to screen
    coordinates.
- ABI summary: Servers need rebuilding, but clients do not;
  . Mirclient ABI unchanged at 8
  . Mircommon ABI bumped to 3
  . Mirplatform ABI bumped to 4
  . Mirserver ABI bumped to 27
- Bug fixes:
  . Add a debug interface to translate from surface to screen coordinates
    (LP: #1346633)
  . Ensure a buffer requested by a surface is not delivered
    after the surface is deleted (LP: #1376324)
  . Overlays are not displayed onscreen in some positions (LP: #1378326)
  . Server aborts when an exception is thrown from the main thread
    (LP: #1378740)
  . Fix race causing lost alarm notifications (LP: #1381925)
  . Avoid lifecycle notifications racing with connection release
    (LP: #1386646)
  . Improve error checking and reporting for the client library
   (LP: #1390388)
  . Mir demo-shell now detects power button using proper Linux scan codes
   (LP: #1303817)
  . A prompt session with an invalid application pid should be an error
    (LP: #1377968)
  . When XDG_RUNTIME_DIR is defined but pointing to a non-existing
    directory use "/tmp" (LP: #1304873)
  . [regression] demo-shell bypass is not used on fullscreen surfaces if
    there are windowed surfaces behind (LP: #1378706)
  . Mir upgrade through dist-upgrade installs incorrect platform
    (LP: #1378995)
  . Fix Mir progressbar example using internal glibc defines(LP: #239272)
  . Stop the default_lifecycle_event_handler raising SIGHUP while
    disconnecting (LP: #1386185)
  . [regression] Mir fails to build with MIR_ENABLE_TESTS=OFF (LP: #1388539)
  . [regression] mir_demo_server_basic does not start (LP: #1391923)