Add meson support

[Sunderland93]

Meson is much simpler and make packaging a lot easier. See #2

[lukefromdc]

In a test build/install to a redirected destination directory
sudo DESTDIR=/home/luke/Desktop/TEST ninja -C build install
all files went to their expected places.

Running
ninja -C build uninstall
fully cleaned out the test destination directory, with no unwanted leftovers. A test with extra files
intentionally added to the created directorys also worked, with ninja not removing the files it did not
add, and leaving the non-empty directories as intended.

We still need to recompile schemas after installing the gsettings overrride, then this will be ready to go.

In autotools the relevent lines are

install-exec-local:
	glib-compile-schemas $(datadir)/glib-2.0/schemas

and at uninstall we run that second line again.

Thank you for doing this, if I knew the meson/ninja build system better I would have included this myself. If necessary, I can research how to run a script from meson/ninja at install time, merge this, then add the schema recompile in a separate commit.

[Sunderland93]

We still need to recompile schemas after installing the gsettings overrride, then this will be ready to go.

I added a script for glib-compile-schemas, please test it

[lukefromdc]

The post install script works, this is ready to go