ENH: change findCell mode in meshRefinement (issue #805)
- in 2.4.x the general default for polyMesh::findCell was FACE_DIAG_TRIS, but this was changed to CELL_TETS for better handling of concave cells. - in snappyHexMesh meshRefinement, findCell is used to define locations in mesh and cells for closer refinement. Using CELL_TETS causes an octree rebuild when the mesh has changed and this adds considerable overhead. For this operation, the faster FACE_DIAG_TRIS mode can be used instead.