Make QPen default to 1-width non-cosmetic.

Make QPen default to 1-width non-cosmetic.

Use the Qt4CompatiblePainting render hint when painting with QPainter to
treat default constructed QPens as cosmetic still.

The NonCosmeticDefaultPen render hint gets documented as obsolete, since
it was in any case not respected by the raster nor OpenGL paint engine.

Change-Id: I04d910e9700baf7f13a8aac07a3633014bb9283e
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>