WIP: buildsystem: switch to using meson
Initial work on #149
What does work:
- Building help
- Installing everything from data except icons (planning to use gresource on those?)
- i18n
What should be discussed first:
- Tests should be executed using ninja test?
- gettext instead of intltool?
- How setup.py works on Windows and how we can just use meson like other GNOME apps does?