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).
# Ignore now accepts \f as whitespace. Operator now includes '**'.
# Ignore and Special now accept \n or \r\n at the end of a line.
# Imagnumber is new. Expfloat is corrected to reject '0e4'.
* test_grammar.py, testall.out: added test for funny things in string literals
* token.py, symbol.py: definitions used with built-in parser module.
* tokenize.py: added double-quote recognition
