Add tool to check for new symbols in GLib/Gio/Gtk

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Update versions of dependencies

GLib 2.34
Gio 2.38

Closes #1 https://github.com/tiliado/diorite/issues/1

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Add Readme

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Merge pull request #1 from tiliado/master

Merge upstream
Merge branch 'master' into feature/travis-ci

* master:
  Add Readme
  Update versions of dependencies
  Add tool to check for new symbols in GLib/Gio/Gtk