Implemented basic Field of View functionality, default angle 45 degrees
Remove unused code, fix initializer
Moved all structs to their own header

Also made OpenCL capable of loading multiple sources files
This way OpenCL and CUDA can use the structs globally defined in gpu_types.h
Added a SAFE( call) macro and fixed OpenCL on CUDA only devices
Also added SAFE macro's to OpenCL

and removed obsolete function declaration
Fix floating point errors with camera movement in FOV code
And restore the normal angle...
Merge branch 'master' into device_rewrite

Conflicts:
	src/devices/opencl.cpp
	src/devices/opencl.h
	src/kernel/kernel.cl
	src/scene.cpp