* Add framework to support more optional types
This PR add a framework to rpc server by using more templates than macros to handle optional types.
Now rpc server recognize both `std/options` and `results.Opt` as optional type for the parameters.
If needed user can add more optional types by overloading `rpc_isOptional` template.
Now aliases to optional types also works.
* Don't expose types used internally by the wrapper