Make Surface own its visibility property

Change-Id: I5eb8ab7bfb16505c8a14c4d77c5ff55aa0e22cfc
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>
Resolve build warning on client code

QString::QString(const char*) is deprecated, wrap thread name
with QStringLiteral.

Change-Id: Ic914d05e7bee6e3f1c6aa0bede44a6b6b85be565
Reviewed-by: Giulio Camuffo <giulio.camuffo@jollamobile.com>