Added Oren-Nayar BxDF, closure.

        - Added Oren-Nayar BRDF, OSL closure.
Updated cmakefiles, OrenNayar.
Added OrenNayar test scenes.
Added OSL OrenNayar shaders.
Added Oren-Nayar OSL shaders.
Added Oren-Nayar OSL test case.
Registering Oren-Nayar to OSL.
Registering Oren-Nayar to OSL, fix typo.
Updated OSL test scene, cleanups.

        - Updated OSL test scenes for Oren-Nayar BxDF.
        - Removed unused variables, minor fixes and cleanups.
Merge branch 'master' of https://github.com/appleseedhq/appleseed into oren_nayar

Conflicts:
	sandbox/tests/test scenes/osl closures/01 - area light - ptne.appleseed
Added Oren-Nayar to BxDF test scene.
Formatting fixes.
Schedule instantiation

When a rendering is active instantiation will not happen right away.
but it will be scheduled. Currently it is possible to instantiate
only an assembly and an object.

This commit fixes issue #327
Fixed mplay tile callback on OSX.
Fixed bug when entering values lower than the min for sliders
Merge pull request #362 from vidarn/master

Fixed bug when entering values lower than the minimum for sliders
Schedule instantiation: coding style fixes

A few thinkg overlooked in the previous commit.
Merge pull request #360 from marius-avram/B327

Schedule instantiation
Add UI button to reset zoom to 1:1:
- create button and icon
- maintain reset zoom independant for each tab
- attach shorcut to button (removed from widgetzoomhandler)
fix #322