autofill for tex modes

[Joe Corneli]

Does anyone know of an autofill (or `fill-individual-paragraphs' type
of function, alternatively & maybe preferably) that works in LaTeX
modes?  I might have written a question about this a couple years ago.
The issue is to avoid messing up the formatting of e.g. large arrays,
while still having "most" lines be 70 characters long or less.  I
think I can write this pretty easily, but if it exists already, that's
even easier.