remove the old _formaldehyde model (not used anywhere)
remove the old _formaldehyde model (not used anywhere)

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