Register a custom class in this using the given name.
If the new class inherits from another Class, the parent should be passed as
parent_class, otherwise null should be used. The optional vtable parameter allows
to provide a custom implementation for handling the class, for example, to handle external properties not added to the prototype. When an
instance of the Class is cleared in the context, destroy_notify is called with the
instance as parameter.
| this |
a Context |
| name |
the class name |
| parent_class |
a Class or null |
| vtable |
an optional ClassVTable or null |
| destroy_notify |
a destroy notifier for class instances |
|
a Class |