[Milestone] v2

[jcbhmr]

• Add partial_interface() decorator
• Add namespace() decorator
• Add partial_namespace() decorator
• Add dictionary() decorator
• Add partial_dictionary() decorator
• Add enum() decorator
• Add callback() decorator
• Add callback_interface() decorator
• Add typedef() decorator
• Add const_() decorator
• Add interface_mixin() decorator
• Add partial_interface_mixin() decorator
• Add some way to apply mixins to interfaces
• Add some way to apply partial interfaces to interfaces
• Add some way to expose interfaces globally
• Add stringifier() decorator
• Add getter() decorator
• Add setter() decorator
• Add deleter() decorator
• Add an overload() router
• Add iterable() decorator
• Add async_iterable() decorator
• Add maplike() decorator
• Add readonly_maplike() decorator
• Add setlike() decorator
• Add readonly_setlike() decorator

[jcbhmr]

Should ES decorators be overloads or separate functions?
Should decorators be PascalCase or camelCase?