Added constructor that takes IEnumerable for Array and IEnumerable<T> for Array<T>.
Added constructor that takes IDictionary for Dictionary and IDictionary<TKey, TValue> for Dictionary<TKey, TValue>.
This property returns an instance of the singleton.
The purpose of this is to allow using methods from the base class like 'Connect'.
Since all Godot singletons inherit Object, the type of the returned instance is Godot.Object.
This allows more consistency in the manner we include core headers,
where previously there would be a mix of absolute, relative and
include path-dependent includes.
Using `misc/scripts/fix_headers.py` on all Godot files.
Some missing header guards were added, and the header inclusion order
was fixed in the Bullet module.
- Allow non-public fields to be exported as well (to avoid confusion).
- Set PROPERTY_HINT_RESOURCE_TYPE for resource derived fields.
- Support enums and automatically fill PROPERTY_HINT_ENUM's hint_string for enum fields.
