Instead of references. This is needed because those function pointers
are used in GDNative which needs to work with plain C, which doesn't
support passing parameters by reference.
The removed check was adding a protection for the case where a `Reference` has not yet got its reference count initialized and a script is called on it. That would cause the object to be released after the call. The removed code was constructing the `Variant` via the `Object` constructor so it didn't deal with the reference count and so the release was prevented.
However, `Variant` no longer works that way so that check was useless. Now it's just illegal to run GDScript on a Reference whose reference count has not been initialized.
- Initialize Object pointer to nullptr so it's not used by mistake.
- When setting an Object check if it's a reference so refcounting works
as intended.
They are now called "utility functions" to avoid confusion with methods
of builtin types, and be consistent with the naming in Variant.
Core utility functions are now available in GDScript. The ones missing
in core are added specifically to GDScript as helpers for convenience.
Some functions were remove when there are better ways to do, reducing
redundancy and cleaning up the global scope.
Almost all instructions need variant arguments. With this change they
are loaded in an array before each instruction call. This makes the
addressing code be localized to less places, improving compilation
overhead and binary size by a small margin.
This should not affect performance.
