Dia 0.97.4

This milestone should stabilise the build process & tests It should not contain any user-visible changes, instead it should focus on getting everything running.

Suggested issues include:

switch to Meson #19
have a working Windows installer neduard/dia#3, #22 (last Windows installer build was 0.97.2 )
ensure the Arch build succeeds #23.
resolve MacOS #10 ( Note that this is present on Sourceforge: https://sourceforge.net/p/dia-installer/support-requests/105/ )
Import Debian Shapes (currently doesn't have issue)
resolve test failures: #8, #7, #6
Better documentation: #5
localisation on Windows: neduard/dia#3 (comment 421267)

Happy to accept suggestions!