We now allow booleanization of all types. This means that empty versions
of all types now evaluate to false. So a Vector2(0,0), Dictionary(),
etc.
This allows you to write GDScript like:
if not Dictionary():
print("Empty dict")
Booleanization can now also no longer fail. There is no more valid flag,
this changes Variant and GDNative API.
Previously godot_variant_new_object constructed Variant without
accounting for the fact that the Object can be a Reference, so refcount
was not increased and References were destructed prematurely.
Also, Reference::init_ref did not propagate refcount increment to the
script instance, which led to desync of refcount info on the script
side and Godot side.
Hein-Pieter van Braam