Lazy drawing

See merge request !43

The application is even lazier now and this is no longer an issue.

When passing an Rc into a gtk callback it causes
the Rust struct to be kept in memory even if the gtk+ wiget
was dropped.

Should have been using Weak refferences all along.

This is preparationg for being able to pass the model to
the connect_craw callback directly.

 See merge request !42

Bit of a hack as we are still creating the window in ::startup but it's good compromise

Pass the arguments to GApplication so we can be launched as a service

Database cleanup

See merge request !41

This is maps better to the MVC naming convention.

If and when such featured are going to be implemented, it should be
trivial to re-add them. Till then there is no reason for them to exist.

When we pass strong reference to callback closures, it prevents
the object to be dropped even if they gtk Widget was destroyed.