add ammonia constants, which have been factored out of the other ammonia codes
add ammonia constants, which have been factored out of the other ammonia
codes

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