Release 2.5.0

ABI summary:

• mirclient dropped
• mirprotobuf dropped
• mircommon ABI bumped to 8
• mirplatform ABI bumped to 23
• mirserver ABI bumped to 56
• mirwayland ABI bumped to 3
• mirplatformgraphics ABI bumped to 19

Enhancements:

• [Wayland] Bump wlr_layer_shell_unstable_v1 version from 3 to 4
• [Wayland] Add focus_mode surface property for Layer Shell
• [Wayland] Add zwp_virtual_keyboard_v1 (closes #2063)
• [Wayland] Add zwp_text_input_v3 & zwp_input_method_v2 (closes #2139)
• [Wayland] Allow zwp_linux_buffer_params_v1.add() with DRM_FORMAT_MOD_INVALID (Fixes #2177)
• [Wayland] Add axis source to pointer events (Fixes #2180)
• [Wayland-platform] Don't block forever in swap_buffers
• Drop mirclient, dependencies on Cap'n Proto & protobuf

Bugs fixed:

• Mir crash when surface and role destroyed in wrong order (Fixes #2055)
• Make GTK's approach to hiding cursors work on Mir (Fixes #2073)
• [input] Handle exceptions while handling udev events
• [input] Fix InputDeviceHub threadsafety
• [Xwayland] Improve popup window types and positioning (Fixes #2037)
• [Xwayland] Use SurfaceStateTracker to track window state (Fixes #1217)