* Compute MD5 hash to deal with nvidia opencl compiler cache not recognizing
changes in #included files, makes it possible to do kernel compile only
once and remember it for the next time blender is started.
* Kernel tweak to compile with ATI/linux. Enabling any more functionality than
simple clay render still chokes the compiler though, without a specific error
message ..
* Fix crash in light path node
* Fix struct alignment issue for cuda
* Fix issue with instances taking up too much memory
* Fix issue with ray visibility working incorrect on some objects
* Enable OpenCL always and remove option, it has no dependencies so may as well
* Refuse to load kernel if OpenCL version < 1.1, recent drivers are needed
* Better error handling for OpenCL device
* 3D views with rendered draw mode will now revert to wireframe on file load
* kernel has shading nodes / textures disabled, amd/nvidia opencl
compilers choke on these, need to figure out how to avoid this
* works in cycles_test, not available as option in blender yet
* kernel compiles and runs with opencl 1.1 from intel/amd/nvidia