Add support for static member functions and static properties

[Ghabry]

Hello.

I'm not completely sure if PushConstructorInspector is a good place for the code but this adds support for static member functions and properties.

The syntax matches the i.method and i.property functions:

class Spaceship {
       [...]
       static std::string name () { return "ship"; }

       static int id;
       static GetId() { return id; }
       static SetId(int _id) { id = _id; }
}

// Inspect:
i.static_method("name", &Spaceship::name);
i.static_property("id", &Spaceship::GetId, &Spaceship::SetId);

// Javascript:
Spaceship.name()
--> "ship"

Spaceship.id = 42
--> <nothing>

Spaceship.id
--> 42

I used "static_"-prefix to make the difference more visual clear because this prevents unintentional bugs.

[vmanucharyan]

Hi! Thanks for contribution! Could you, please, also add some tests for this?

[mean-ui-thread]

I want that feature too!

[Ghabry]

Okay I will try to make up a few tests.
Except for the registration logic in duktape I used the already existing code for argument and return vaule handling, therefore I will keep the test suite small.

[vmanucharyan]

@Ghabry I think one high level test for property and one for static method will be enough (just check that it is callable from js). lower level logic such as passing around arguments and return values is already tested