Add get/setPart to ITiledRenderable, and implement for sw/sc.

Change-Id: Iec3d6374f029149cadf8fb9c9b16fec90146c31e
LOK DocView: implement part selection.

Change-Id: I2e16ca9d2d5fcd25b0435f1b9b0fbcb52b92e012
Add part selector to gtktiledviewer.

Change-Id: I569c8f0ebf4476c0a247cde15a263d1db956a14b
Add Tiled Rendering outline to sd.

Change-Id: I810d827f330690f8071b662b9ddd05cc41655a71