Added ability to get list of editor settings changed when saving editor settings. Optimised settings changed notification.

[EricEzaM]

Getting the settings which were changed has been a common request. This also allows for some optimisation.

Debug build time savings
Saving settings 'hitch' before: 1000ms
Saving settings 'hitch' after: 350ms

There is still time to be gained, for example in EditorInspector, update_tree() takes 0.25ms to run, but I am not sure why this is called when editor settings are changed. What changes is it responding to? Once we know that, then a check can be added to only conditionally run that method (e.g. if it is only changing due to theme changes)

godothing.mp4

[EricEzaM]

Also it turns out when you change a shortcut, set is not actually called in editor settings. The shortcut's memory is changed directly, and then when the settings are saved, get is called and the new shortcut is read. So for shortcuts, I have just added a generic shortcuts and builtin_action_overrides strings which will be added to the changed_settings array when those are changed.

[KoBeWi]

Looks good overall. We should probably go over all uses of NOTIFICATION_EDITOR_SETTINGS_CHANGED and only update when necessary, but this can be done in a follow-up PR.

[akien-mga]

The new methods should be synced in the class reference (and documented): https://github.com/godotengine/godot/runs/3916673006?check_suite_focus=true

[KoBeWi]

@EricEzaM It would be nice to have this finished and merged. Aside from speed ups, it helps to fix some annoying issues.

[EricEzaM]

Made changes as per request, added documentation.

[KoBeWi]

This error appears when changing actions:

Cannot mark nonexistent setting as changed: builtin_action_overrides

And this when changing shortcuts:

Cannot mark nonexistent setting as changed: shortcuts

Everything else looks ok.

[EricEzaM]

This error appears when changing actions:

Cannot mark nonexistent setting as changed: builtin_action_overrides

And this when changing shortcuts:

Cannot mark nonexistent setting as changed: shortcuts

Everything else looks ok.

Ah bugger, I added that last minute for validation that the setting passed to the mark as changed method actually exists. I guess I will remove it, I was uncertain about adding it in the first place anyway.

[akien-mga]

Thanks!