todo

麻省理工的计算光子晶体的程序

Add more example files: more 3d crystals, strip waveguide, ...

Export/import DXF, VRML, POV, ...?  Import full epsilon tensor from a file.

Make mpb-data pick default -n when -r is used.

More eigensolver improvements...adaptive selection of an iteration technique?

Try Jacobi-Davidson method with harmonic eigenvalues for targeted solver.

World domination.