#297 QwtAbstractScaleDraw kills the renderFlags of the labels

[Uwe Rathmann]

QwtAbstractScaleDraw::tickLabel sets the renderFlags of the QwtText being returned from label() explicitely to 0. That might have been implemented under the assupmtion, that the tick labels are always rendered into a minimal rectangle, where nothing has to be aligned.

But when the label consists of more than one line that is not true.