[mutter] (12 commits) Non-fast-forward update to branch wip/nielsdg/meta-plugin-derivable

[Niels De Graef <nielsdg src gnome org>]

The branch 'wip/nielsdg/meta-plugin-derivable' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  3687250... meta/plugin: Use G_DECLARE_DERIVABLE_TYPE

Commits added to the branch:

  576cd08... core: Rename MetaStartupNotificationSequence to MetaStartup (*)
  26fbd56... x11: Refactor the X11 startup notification bits into src/x1 (*)
  91ce24d... core: Add extra properties to MetaStartupSequence (*)
  8a10196... x11: Set all MetaStartupSequence properties for libsn seque (*)
  4a69a0d... core: Shuffle startup notification object creation (*)
  4d92979... core: Make MetaStartupSequence/Notification public (*)
  ec6a536... core: Use MetaStartupSequence internally (*)
  7635d06... core: Drop MetaDisplay startup sequence API (*)
  92349a4... wayland: Complete the startup sequence as given from gtk-sh (*)
  6b7bd91... x11: Complete X11 startup sequence on SN_MONITOR_EVENT_COMP (*)
  e11ee44... core: Refactor/simplify display startup sequence handling (*)
  ca7c5c1... meta/plugin: Use G_DECLARE_DERIVABLE_TYPE

(*) This commit already existed in another branch; no separate mail sent