Minimal bounding spheres for points

This introduces a method to create smallest enclosing spheres for an arbitrary number of points.
The implementation is a bit tricky due to the recursive nature of the algorithm but according to the papers it has a near linear runtime even for high-dimensional sets of points.
I will need this functionality for a mesh element quality metric (radius to shortest edge ratio) that is especially useful for the tetrahedral meshes we can now create. (You may know this from ParaView.)

I referenced the papers this is based on in the source file, if anyone is interested I can provide you either with PDFs or the printouts.
What is the current policy on this? I seem to remember something like Lars saying we should keep writing "2013" until we fix this for all files.
Actually it should read (c) 2012-2014 everywhere ....