Gletters: first version

Hi,

this is a first version gletters. Contains Wordlist.qml in core/ for wordlist handling plus a xml->json converter script. All default-XX.xml files found in Gtk+' gletters have been included as .json files.

This version lacks android support. As discussed on IRC there seems to be no way to use the Android virtual keyboard for generating and catching key-events. Will retry or implement a way in qml. You can wait with the merge until the Android stuff is finished if you prefer.

Thanks, Regards,
  Holger