Implement 'static' and 'constructor' directives

[IvanSanchez]

Pretty much like method and function, but labelled as "Static methods" instead.

Also implement a constructor directive, pretty much like factory but allowing namespaces instead of identifiers (i.e. dots) and printing "new", e.g. new L.Draggable

[IvanSanchez]

I think this is covered by the "custom documentables" functionality already.