Port the build system from Autotools to Meson
Port the build system from Autotools to Meson.
Requirement: follow as closely as possible the same Meson coding style as in Tepl. gspell has a very similar structure.
I'm not going to do this work anytime soon, gspell is in low-maintenance mode, it has everything I need and it works fine. But contribution welcome, I would be happy to review a merge request, to finally get rid of Autotools, slowly but surely.