* Add function contracts.

* Use contract in place of reference.

* Add permissible single return support.

* Provide contract in signature during verification.

* Allow contract in function creation.

* No longer defer basic use to contract.

* Add contract to clamp function.

* Add tests for singular clamping.

* Update src/test/skript/tests/syntaxes/functions/clamp.sk

Co-authored-by: Patrick Miller <apickledwalrus@gmail.com>

* Sorry nice annotation, you're going to a "better" place :(

* Move stuff around in circles.

* Sovde made me change the assertions. :(

* Move everything (again)

* Add null annotation.

---------

Co-authored-by: Patrick Miller <apickledwalrus@gmail.com>
Co-authored-by: sovdee <10354869+sovdeeth@users.noreply.github.com>