Fatband plots

It would be nice to provide fatband plots here as well by reading in Lobster outputs.

We would need a KPOINTS file (maybe a KPOINTS.lobster, @davschnieders?) and a way to read the Efermi level (vasprun.xml or something else) to make it work for anything beyond VASP.

I would also need to test if the current implementation in pymatgen works with any KPOINTS file or only certain types.