bugfixes for some cube-loading issues noted by @jpinedaf
bugfixes for some cube-loading issues noted by @jpinedaf

e-koch/pyspeckit,e-koch/pyspeckit,vlas-sokolov/pyspeckit,allisony/pyspeckit,pyspeckit/pyspeckit,keflavich/pyspeckit,keflavich/pyspeckit,allisony/pyspeckit,jpinedaf/pyspeckit,vlas-sokolov/pyspeckit,low-sky/pyspeckit,pyspeckit/pyspeckit,jpinedaf/pyspeckit,low-sky/pyspeckit