Add meson build system (#1)

Initial meson build system support. We do not create .desktop file yet, but we need an option to open media files from GUI first anyway.

meson.build

@@ -0,0 +1,26 @@
+project('com.github.rafostar.Clapper',
+  version: '0.0.0',
+  meson_version: '>= 0.47.0',
+  license: 'GPL3',
+  default_options: [ 'warning_level=2' ]
+)
+
+python = import('python3')
+python_bin = python.find_python()
+
+if not python_bin.found()
+    error('No valid python3 binary found')
+endif
+
+conf = configuration_data()
+conf.set('bindir', join_paths(get_option('prefix'), 'bin'))
+
+subdir('bin')
+subdir('gjs-1.0')
+
+installdir = join_paths(get_option('prefix'), 'share', meson.project_name())
+install_subdir('clapper_src', install_dir : installdir)
+install_subdir('css', install_dir : installdir)
+install_data('main.js', install_dir : installdir)
+
+meson.add_install_script('build-aux/meson/postinstall.py')