Cycles: Fixed broken displacement

Cycles: Fixed broken bump mapping

Cycles: improved texture differentials for bump maps, added texture differntials to displacement maps

Cycles: added ray differentials to henyey-greenstein phase function

Cycles: Moved texture coordinate differential creation to after all bump maps are created. This should improve texture caching in scenes with bump/displacement maps.

Cycles: Fixes for texture caching, behavior with auto convert off was broken, color space was misinterpreted sometimes.
Note: Texturing with OSL is currently broken.

Cycles: Smaller fixes for differentials, taking dNdu inot account when getting N from a bump shader

Ccyles: texture differentials now respect the hidden mapping node inside the image texture node.

Cycles: fix for mip map paths

Cycles: Changed Mip Map names to replace, not add to suffix
Added oiio_make_tx() call to Cycles' Python API

Cycles: improved ray differentials for specular/glossy closures with DNDU/V enabled

Cycles: more accurate differential approximation for glossy bounces

Cycles: Don?t apply glossy blur texture filtering on singular paths

Cycles: fixed normal differentials, ShaderData now contains dNdx/y instead of dNdu/v

Cycles: added diffuse_blur and glossy_blur parameters to texture cache

Cycles: Smaller updates to texture cache, setting a few more options and letting textureSys do the flipping instead of doing it manually

Cycles: fixed include statements for image cache to work on case-sensitive file systems

Cycles: added blurrier texture lookups for indirect diffuse paths

Cycles: Added dPdu/dPdv to area ligths so we can use filtered textures on them

Cycles: Cached textures are now assumed to be linear and converted from sRGB during texture filtering where necessary