ENH: Adds mesh data memory layout optimizer

Adds optimizer to the mesh. This algorithm rewires
the node order and triangle connectivity to optimize
for memory layout. Adds tests for the same.

The algorithm starts with a random node and flood-fills
in the triangular mesh space adds nodes and elements
at every iteration. The iteration ends when the surface
is "flooded". The algorithm assumes that the mesh is
one topologically connected entity.

TODO: Further optimization at each iteration. Extend to other mesh types.