Updated to svn revision 57841
Fix convert_float4, disable bvh trace, reorganize cmake kernel compile
options and add CMAKE_CXX_FLAGS to optimized kernel command lines,
vectorize bvh_inverse_direction, vectorize bvh_triangle_intersect, made
frac(float,int*) branchless, reordered interp(float,float,bool), made
quick_floor(float) branchless, vectorized fade(float), added
copysign(T,T) unit test.