Port build system to meson
This superseeds !7 (closed), which conflicted with new changes into the source code and I wasn't able to solve it.
Changing the build system from autotools to meson (just like many other GNOME software) provides the following advantages:
- cleaner and simpler build instructions
- enables Damned Lies to read/set language codes from/to
LINGUASfile (see this e-mail), therefore not required Git access for each translator for adding new translation to .po files.
Please notice this merge request does not include dropping Autotools support to avoid file conflicts, but all it takes is removing