Move by QLatin1Char

Summary:

• Add new AtCore::move(QLatin1Char ) override.
• allow movement to be negitive (in case of relative movements)
• update test client to use new functions

Reviewers: laysrodrigues, patrickelectric, tcanabrava

Reviewed By: laysrodrigues, patrickelectric

Differential Revision: https://phabricator.kde.org/D10840