Correct handling of font weights bolder than bold.

A couple of places were checking for a font weight equal to QFont::Bold
rather than a weight that is greater or equal to this. This sometimes
results in QFont::Black being rendered with a lighter weight than
QFont::Bold even though it should if anything be heavier.

Change-Id: I5aa73a84ea2718783bbac93a031d87b2ad90012c
Reviewed-by: Rafael Roquetto <rafael.roquetto@kdab.com>
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Fix settable style hints.

Introduce QStyleHintsPrivate and introduce internal
setters called by QApplication.

Task-number: QTBUG-33991
Change-Id: Id61f8b1e2b5c9cfd7b4713aaded66e93e6f63719
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>
Reviewed-by: Andy Shaw <andy.shaw@digia.com>
Fix a bug in QSqlQuery::isNull documentation

the method returns true if there is not such field.

Change-Id: I25db8de4561d3e0604f3e64edc1810140ba4aad2
Reviewed-by: Andy Shaw <andy.shaw@digia.com>
Reviewed-by: Mark Brand <mabrand@mabrand.nl>