Merge gd4 branch to master

[fire]

@Geequlim

What do you think about?

1. Branch master to be godot3
2. Merging gd4 to master?

[why-try313]

@fire Some things to consider:

• The project isn't what we could call "stable", setting it as master might not be the better choice
• The guys from the main repo move fast, master is now Godot 4.1 (dev) and could lead to confusion

But overall, at some point it would be great to have Godot 4.0rc Javascript module as master indeed

[fire]

I'll check back later when Godot Engine 4.0 / Javascript module is considered more stable.