* Make sure all source files have a LGPL copyright header, and standardize
non-standard variations of the header to a common form.
* Check and update all copyright notices.
* Remove 'Written By:' lines. They are universally incomplete and
typically indicate only who started a particular file.
https://bugzilla.gnome.org/show_bug.cgi?id=634550
Currently the size of an StGroup depends exclusively on the group's
children - it should be possible to override this behaviour with
fixed values in the CSS.
https://bugzilla.gnome.org/show_bug.cgi?id=613907