Trace on Variable assignment

[Scott Lystig Fritchie]

Sean's wish is on our wishlist in the Sendmail EUC '00 paper.  I might
have called them "conditional breakpoints".  Ah, no, I said,
"conditional watchpoint".  Hrm.  "Conditional breakpoint" would've
been better, I think.  Editing seems to work much like hindsight
does....

The alternative right now is to modify the code you're debugging to
something like:

	Want_to_watch = Whatever(),
	if
		Want_to_watch = desired_term() -> ok; % Breakpoint here
		true                           -> ok
	end,

... which is annoying.  And if the compiler were sufficiently
aggressive, you might be surprised by having your breakpoint
disappear.

-Scott