overrides for message-dialog, window, tree-view and tree-store with relatives

With this I provide all overrides necessary to migrate all existing opine widgets to gir-ffi-gtk3.
You may want to give me commit access to the repository as I expect to maintain much of the codebase while giving life to opine.

Enjoy,
Patrick

Since the rest of GirFFI does not support named arguments at the moment, adding them here does not seem right. Please change them to positional arguments. GirFFI is not meant to be a complete drop-in replacement for Ruby-GNOME2.