99% of the time we shouldn't rely on the signal, we
should use the notification instead. I left some comments
in places where I couldn't quickly improve the code.
* Works for binary and text files.
* Makes EditorQuickOpen work with custom resources again.
* Information is cached and easily accessible.
Properly fixes#66179. Supersedes #66215 and supersedes #62417
**WARNING**: This required breaking backwards binary compatibility (.res and .scn files). Files saved after this PR is merged will no longer open in any earlier versions of Godot.
As many open source projects have started doing it, we're removing the
current year from the copyright notice, so that we don't need to bump
it every year.
It seems like only the first year of publication is technically
relevant for copyright notices, and even that seems to be something
that many companies stopped listing altogether (in a version controlled
codebase, the commits are a much better source of date of publication
than a hardcoded copyright statement).
We also now list Godot Engine contributors first as we're collectively
the current maintainers of the project, and we clarify that the
"exclusive" copyright of the co-founders covers the timespan before
opensourcing (their further contributions are included as part of Godot
Engine contributors).
Also fixed "cf." Frenchism - it's meant as "refer to / see".
