* Add void prototype to NativeCall typeset
`void` prototype can be used for simple natives which don't return any value.
This is done to silence compiler warnings 209 (`function has explicit 'int' tag but does not return a value`) and 242 (`function "NativeCallback" should return an explicit value`).
* Make MenuHandler into typeset and add void prototype
This can be used for basic menu handlers that don't return modified item styles and don't redraw menu items.
