[Groff] footnotes without implicit paragraph break

[Dorai Sitaram]

Is there a way to modify ms's .FS macros so that successive footnotes on
the same page are accumulated without an intervening implicit paragraph
break?  Of course, the user should be able to deliberately insert a
parbreak if they so choose.

Rationale: When footnotes are really small, like the "Ibid." or "Op.
cit." of yore, say, and don't deserve to take up a whole line.

--d