heterodyne: Hardwire recipe parameters for Legacy reductions.

Graham thought that this was easier than modifying jsawrapdr, although
I believe we had planned to have a legacy recpars file.
heterodyne: Put PRODUCT argument description in alphabetical order.
heterodyne: Do not trim or rebin in the legacy recipe.

Sarah wants to deal with rebinning during the coaddition, and
isn't convinced of the need to trim.  It's easy to handle this later,
but not if we rebin and trim in the legacy recipe.

Note there are conflicts between Scicom Trac tickets 373 and 376/396.