D13641: [KCharSelect] Port generate-datafile.py to Python 3

[Christoph Feck]

cfeck requested review of this revision.

REPOSITORY
  R236 KWidgetsAddons

REVISION DETAIL
  https://phabricator.kde.org/D13641

To: cfeck, #frameworks, lbeltrame
Cc: kde-frameworks-devel, michaelh, ngraham, bruns