[retro-gtk] (9 commits) Non-fast-forward update to branch core-fixes

[Adrien Plazas <aplazas src gnome org>]

The branch 'core-fixes' 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:

  148fae5... core: Document the iterated signal
  51e72d8... core: Improve the runahead property documentation
  e06e207... core: Typo, quote and apostrophe fix
  61bf5c6... core: Fix a precondition in retro_core_override_option_defa
  d6f8607... core: Make keyboard_widget_notify() static
  7307f62... core: Make controller_state_changed_cb() static
  af34e76... core: Check controller in retro_core_set_default_controller
  dc84f24... core: Check controller in retro_core_set_controller()

Commits added to the branch:

  c38dc04... core: Make it a singleton (*)
  ffe2d9f... core: Document the iterated signal
  d1a691b... core: Improve the runahead property documentation
  388e1d7... core: Typo, quote and apostrophe fix
  9d81cae... core: Fix a precondition in retro_core_override_option_defa
  2a7abec... core: Make keyboard_widget_notify() static
  349e254... core: Make controller_state_changed_cb() static
  b935f18... core: Check controller in retro_core_set_default_controller
  7bb2f2f... core: Check controller in retro_core_set_controller()

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