Frame deltas are currently measured by querying the OS timer each frame. This is subject to random error. Frame delta smoothing instead filters the delta read from the OS by replacing it with the refresh rate delta wherever possible.
This PR also contains code to estimate the refresh rate based on the input deltas, without reading the refresh rate from the host OS.
The delta_smooth_enabled setting can also be modified at runtime through OS::, and there is also now a command line setting to override the project setting.
* This should optimize GDScript function calling _enormously_.
* It also should simplify the GDScript VM considerably.
NOTE: GDExtension calling performance has most likely been affected until going via ptrcall is fixed.
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".