Merge pull request #15 from disjukr/master

Export model as ply format
Add fov slider.
The camera can now rotate around the picking point...phiou!.
Add normal shader + update manifest-build+few fixes.
Code clean up.
Fix normal shader + rename variable in camera.
Replace normal shader...
Do not use camera pivot by default + update build.
Add back screenspace normal shader + small fix for camera reset.