Change number of Doxygen columns to 3.
Change number of Doxygen columns to 3.

Thanks @dmcdougall for bringing up this issue.

Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh