heterodyne: Protect FINDCLUMPS against crazy artefactual values.

This addresses Fault 20130612.006.  While the large value that
FINDCLUMPS was invited to contour to separate clumps originated in
MFITTREND, it is a quicker fix than getting to the bottom of why one
edge baseline voxel was c. -dex9 (positive once subtracted).  Also
generating an abnormal value is always a possibility while fitting to
noisy data.  The chosen range should not exclude any known
astronomical signal and make the maximum number of contours in
FINDBACK more manageable.
heterodyne: Wrap parameter list to fit in a normal terminal width.
heterodyne: Enable and document recipe parameters in lineforest recipe.
heterodyne: Add bad-spectra filtering to the lineforest recipe.
heterodyne: Correct and augment the prologue of REDUCE_SCIENCE_LINEFOREST.

Mostly adding defaults, with a few typo's corrected.  Demanding that
the user supply a decimal place is no longer needed in velocities as the
primitives take care of this.
heterodyne: Add licence.