* Added option for importers to show an Advanced settings dialog
* Created advanced settings dialog for Scene Importer
* Cleaned up importers (remove many old/unused options)
* Added the ability to customize every node, material, mesh and animation individually
* Saving to animations and meshes to files is now a manual process, making it more predictable
* Added the ability for materials to be replaced by external files (or to be made external, up to you).
* When doubleclicking an impoted scene in the filesystem dock, it automatically shows the import settings instead of asking to open it.
WARNING: Lightmap UV unwrap is not working, it needs to be re-made.
This fix request_completed being emitted two times, the first with the
result, the second as a failure when retrieving responses served with
read-until-EOF.
* Adds both a preview sun and preview environment to the 3D editor.
* They are valid as long as a DirectionalLight3D and WorldEnvironment are not in the scene.
* If any is added to the scene, the respective preview is disabled.
* Changed WorldEnvironment to better handle multiple node versions.
* Added a function in SceneTree to get the first node in a group.
* Fixed button minimum size to also consider font height if no text is there, this broke with the TextSever PR.
This makes them easier to distinguish, especially when used
in a TileMap.
The default color's opacity has been slightly decreased to account
for the new outline.
Renamed to ActionMapEditor as it is more generic and can be used for more than just the InputMapEditor if required.
This also includes a new Event Configuration dialog (previously "Press A key...") which can be used to create and edit InputEvents for any use - like the Project Settings input map, or the Editor Settings shortcuts.
Implements https://github.com/godotengine/godot-proposals/issues/1835#issuecomment-727186192
* PauseMode is now ProcessMode, containing the following states:
```
PROCESS_MODE_INHERIT, // same as parent node
PROCESS_MODE_NORMAL, // process only if not paused
PROCESS_MODE_PAUSE_ONLY, // process only if paused
PROCESS_MODE_ALWAYS, // process always
PROCESS_MODE_DISABLED, // never process
```
* NOTIFICATION_PAUSED and NOTIFICATION_UNPAUSED are received effectively when the node is paused and unpaused (not any longer when pause mode is set in SceneTree).
* Renamed some nodes that used ProcessMode/process_mode to specify a callback type to ProcessCallback to avoid clashes.
