Add handling of pure magnetic (B) fields read from CST ASCII data.#124

ChristopherMayes merged 3 commits intoChristopherMayes:masterChristopherMayes/openPMD-beamphysics:masterfrom

ColwynGulliford:fix_cst_reader_for_zero_sized_along_coord_vecColwynGulliford/openPMD-beamphysics:fix_cst_reader_for_zero_sized_along_coord_vecCopy head branch name to clipboard