Paint system

* Add unified color settings to brush menus.
* Add notifier on fill tool from drag and drop to refresh icons
Minor polishing, add UV layer selection in image projection painting
mode.
Another minor correction, use "Mask" instead of "Stencil" so users can
correlate the panel to the mask tool.
Last minute artist feedback tweak: Fill tool should not use masking
apart from stencil(texture) and face masks.
Py Template: Set the active object in batch export

Some exporters (mdd for example), only use the active object
Fix T41890: Regression in new array modifier code, vnors were no more offset-corrected.

This is not needed when we tag normals as dirty, but in simple cases, if offset has some
rotation (or non-uniform scaling) component, vertex normals has to be corrected.
Tracking: Fix ground plane normal facing downwards
Fix T41754, sunbeams node should return the unmodified source value at
the source pixel.
Fix T41902: Flipped persp/ortho region_2d_to_vector_3d

- Ortho result from view3d_utils.region_2d_to_vector_3d was flipped.
- Persp result wasn't normalized.
- operator_modal_view3d_raycast.py failed for ortho views.

Thanks to Philipp Oeser for the initial fix.
Correct MAX_LIBARRAY define, assert when its wrong
Fix image.save() - incorrect relative lib path
Corrent recent commit: off by one error
Fix T41891: Alt+S can't save image

win32 BLI_path_abs expanded empty strings into "C:\\",
which made BLI_exists succeed (quite confusing).

Now match behavior on *nix.
Fix for Freestyle crash in bordered animation rendering
Freestyle: disallow with fields (was crashing)
Projective painting:

* Make clone UI a bit more descriptive
* Don't set images to image editors that have a pinned image.
Merge remote-tracking branch 'origin/master' into multiview

Conflicts:
	source/blender/render/intern/source/pipeline.c
Viewport 3D: Drawing of Stereo Cameras, Convergence Plane and Volume

This also includes:
* Unification of the view_matrix and model_matrix functions.
* Fix for Toe-in formula
* Fix for viewport bug when camera scale was not uniform