Add command line option for setting the number of threads.
Submodule fost-base 8d4c396..aa54684 (rewind):

< Fix a problem where a temporary result was being returned.
  < We can't make use of C++11 features in this part of the code base.
Allow the super sampling to be passed in on the command line.
Use the intersection type from the first item.
We have a gloss sphere type.
Rename the old compount class to collection.
Skeleton for new compound type with expected use.
Surface should be default constructable.
We now need to change how the geometry is set up.
Make sure we can realy tell when we need to implement the reflectance.
Start to implement a new intersection type.
Handle the basic methods needed by an intersection.
Transforms the reflective sphere.
Return the closest intersection to the ray start position.
Put the reflective sphere first.
Do the correct occlusion check.
Lift out the intersection template.
Start to build the shader forwarder, but clang 3.2 crashes
Have to pass the entire scene into the shader calculation.
We need to manually create a closure to capture the other parameters.