Added mailmap file so git gather committers statistics properly.
Added mailmap file so git gather committers statistics properly.

Hipparchus-Math/hipparchus,Hipparchus-Math/hipparchus,sdinot/hipparchus,sdinot/hipparchus,sdinot/hipparchus,Hipparchus-Math/hipparchus,Hipparchus-Math/hipparchus,sdinot/hipparchus