Auto-instantiation is used by the create dialog, but should also be
used by the editor inspector.
This refactors object properties auto-instantiation into a dedicated
method to be reused throughout editor (and possibly scripting).
When clicking on a resource field in the inspector dock, you now have
the "Quick Load" option in addition to "Load". This opens a QuickOpen
dialog allowing the user to type in a phrase to quickly locate the
desired resource (similar to "Quick Open Scene").
In my experience, this is much faster than clicking through the File
Dialog.
Relates to godotengine/godot-proposals#346.
* Added a new macro SNAME() that constructs and caches a local stringname.
* Subsequent usages use the cached version.
* Since these use a global static variable, a second refcounter of static usages need to be kept for cleanup time.
* Replaced all theme usages by this new macro.
* Replace all signal emission usages by this new macro.
* Replace all call_deferred usages by this new macro.
This is part of ongoing work to optimize GUI and the editor.
* LineEdit popups created on demand.
* TextEdit popups created on demand.
* SpinSlider popups created on demand.
* ResourcePicker popups created on demand.
Improves editor responsiveness.
