Added a general block size routine for parallel computation.
Added a general block size routine for parallel computation.

This can be useful in some situations (but frankly, not very much ;-)

Alwnikrotikz/numexpr,ooguntola/numexpr,Alwnikrotikz/numexpr,ooguntola/numexpr,tectronics/numexpr,ooguntola/numexpr,tectronics/numexpr,tectronics/numexpr,Alwnikrotikz/numexpr