tokenize.py has always used naive regexps for matching string literals,
and that appears to trigger the sre recursion limit on Skip's platform (he
has very long single-line string literals).  Replaced all of tokenize.py's
string regexps with the "unrolled" forms used in IDLE, where they're known to
handle even absurd (multi-megabyte!) string literals without trouble.  See
Friedl's book for explanation (at heart, the naive regexps create a backtracking
choice point for each character in the literal, while the unrolled forms create
none).