Fixes #83

Not sure why this is suddenly needed, but whatever.

Fixes #84

Suggested by Pedro Paulo. This doesn't make much difference to the UI,
but it works and it's nice, so why not?

The box underneath navigation_box isn't accomplishing anything.

-w got lost in the port from Autotools to Vala. We shouldn't emit C
compiler warnings because this isn't a C project.

It's possible for there to be no King if we're running unit tests rather
than a real game.

It's been 11 years. I guess I can say I'm an author by now.

For adaptive dialogs

For GtkFileDialog

But actually keep using it. This just suppresses the deprecation
warning, because it's impossible to stop using it.

This is based on GTK's internal gdk_texture_new_for_surface(), rewritten
in Vala.

Probably fixes #91, though I haven't been able to reproduce the problem
myself.

This is a workaround for vala#1104

Fixes #92

The toast is a modern way to do notifications without needing to use
banners.

The mirrors are unreliable, and at least one is serving a tarball that
is different than expected....

Includes all the dependencies that must be installed, as well as the commands needed to properly build and run the program.

Fixes #72.