QmlDesigner.PropertyEditor: Adding sheet for QtQuick.Window

Change-Id: I99eee33ee7557aa94069b4dc999cb9f9a711caaa
Reviewed-by: Marco Bubke <marco.bubke@digia.com>
QmlDesigner: Rename margins to padding

The old name was misleading.

Change-Id: I253b21530e0f2c7c68c4850190d791aeb8567172
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>