Building gtkmm-documentation with meson

[Kjell Ahlstedt <kjellahlstedt gmail com>]

I have added meson.build files to the master branch of gtkmm-documentation in gitlab.gnome.org.
If you want to test it, please do. Read the README file for instructions. I hope meson can soon replace autotools for building gtkmm-documentation.

Question: docs/tutorial/Makefile.am contains commands for building the documentation in epub and mobi formats. These builds are said to be experimental. Does anyone know if they are used or useful? The meson.build files don't contain these build commands. Should they be added there?

After having worked with meson for a few weeks, I find it better than autotools in several respects. For example, the meson.build files are easier to read and understand than Makefile.am. It has two restrictions, though:

1. Each build rule defined with custom_target(), can contain only one command.
2. A built file must be stored in the same directory as the meson.build file where the build rule is defined. (Actually the corresponding directory in the build tree.)

Restriction 2 is probably the reason why glib and gtk contains more than 50 meson.build files. I have to some extent used script files to work around these restrictions.