Access rules for setters and getters

[eon-s]

Haxe has an interesting approach to access options for setters and getters, even when there's public and protected keywords for visibility, access control can add more options.

public var x(default, set):Int;

function set_x(newX) {
  return x = newX;
}

Details:
https://haxe.org/manual/class-field-property.html

Using that kind of rules may be enough to cover the needs of Godot games, frameworks and plugins.

Related proposal:
#2979

[azur-wolve]

access specifiers is something that I miss in GDScript, for good code OOP design