When using the presenter console, the secondary screen has
a small view of the current slide.

Currently nothing clips the shapes that are on the slide,
so they may be rendered outside the slide rectangle,
because there's a single VCL-canvas and OutPutDevice that covers
the entire screen.

Set up some brute force clipping in DrawShape::getViewRenderArgs().

Change-Id: I3b21f08c12718254b6cf166b7fb1540e9381b243