This now does a dynamic analysis of which elements are so frequently
repeated as to constitute noise. The primary benefit is an enormous
speedup in find_longest_match, as the innermost loop can have factors
of 100s less potential matches to worry about, in cases where the
sequences have many duplicate elements. In effect, this zooms in on
sequences of non-ubiquitous elements now.
While I like what I've seen of the effects so far, I still consider
this experimental. Please give it a try!
When describing a Boolean return value, use "true" and "false" instead of
"1" and "0".
Style-guide conformance: no "iff" -- to obscure for many readers. ;-(
Documentation for difflib/ndiff refactoring: more of the ndiff functionality
has been moved to the underlying library (difflib).
This closes SF patch #445413.
