Remove QWindow pos, geometry and size as properties; pos->position

Remove QWindow pos, geometry and size as properties; pos->position

Abbreviated properties are to be avoided.  But all 3 of these
properties are redundant from the QML perspective; and because QRect,
QPoint and QSize are (wisely) not QObjects, it's not possible to bind
to _their_ properties, which make these QWindow properties less useful
than users might assume that they are.

Change-Id: I19c00b54b1d2712f9418e8bcf56e35a8008b89ef
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>