Upgrading to Godot 4.1

[isirode]

Hello,

This is a PR to upgrade the project to Godot 4.1.

I am not sure if the example.gd replacements are rigorously the equivalent, but I suppose there are a lot of variables that are monitorable and that the end user will pick the one he want.

You might want to historize the Godot 3 version in another branch if you accept this PR.

Thank you in advance,

PS: thank you for the project, it's awesome 😀

[aleksandrbazhin]

Thanks, I will check the PR when I have time, most likely this weekend. Glad you found the project helpful. I don't use lately, so your input is very appreciated.

[isirode]

I've noticed I did not rename the "function_ref" methods (yours), let me know if you think we should rename them.

[aleksandrbazhin]

Hi! Sorry, I was not able to look into it yet. I keep it in mind and do it as soon as I have time.