speedups for certain unicode character ranges.

- take locale into account for word boundary anchors (#410271)
- restored 2.0's *? behaviour (#233283, #408936 and others)
- speed up re.sub/re.subn

- removed __all__ cruft from internal modules (sorry, skip)
- don't assume ASCII for string escapes (sorry, per)

to be exported

also modified check_all function to suppress all warnings since they aren't
relevant to what this test is doing (allows quiet checking of regsub, for
instance)

by compiler/engine mismatches

-- added some more docstrings
-- fixed typo in scanner class (#125531)
-- the multiline flag (?m) should't affect the \Z operator (#127259)
-- fixed non-greedy backtracking bug (#123769, #127259)
-- added sre.DEBUG flag (currently dumps the parsed pattern structure)
-- fixed a couple of glitches in groupdict (the #126587 memory leak
   had already been fixed by AMK)

-- added REPEAT_ONE operator
-- added ANY_ALL operator (used to represent "(?s).")

-- reverted REPEAT operator to use "repeat context" strategy
   (from 0.8.X), but done right this time.
-- got rid of backtracking stack; use nested SRE_MATCH calls
   instead (should probably put it back again in 0.9.9 ;-)
-- properly reset state in scanner mode
-- don't use aggressive inlining by default

 + added "regs" attribute
 + fixed "pos" and "endpos" attributes
 + reset "lastindex" and "lastgroup" in scanner methods
 + removed (?P#id) syntax; the "lastindex" and "lastgroup"
   attributes are now always set
 + removed string module dependencies in sre_parse
 + better debugging support in sre_parse
 + various tweaks to build under 1.5.2

comments, docstrings or error messages. I fixed two minor things in
test_winreg.py ("didn't" -> "Didn't" and "Didnt" -> "Didn't").

There is a minor style issue involved: Guido seems to have preferred English
grammar (behaviour, honour) in a couple places. This patch changes that to
American, which is the more prominent style in the source. I prefer English
myself, so if English is preferred, I'd be happy to supply a patch myself ;)

- changed "group" operator to "groupref"

  used by the code generator)

- changed max repeat value in engine (to match earlier array fix)

- added experimental "which part matched?" mechanism to sre; see
  http://hem.passagen.se/eff/2000_07_01_bot-archive.htm#416954
  or python-dev for details.

   speedup for some tests, including the python tokenizer.

-- added support for an optional charset anchor to the engine
   (currently unused by the code generator).

-- removed workaround for array module bug.

-- changed 1.6 to 2.0 in the file headers

-- fixed ISALNUM macro for the unicode locale.  this
   solution isn't perfect, but the best I can do with
   Python's current unicode database.

- untabified sre_constants.py

  (those semantics are weird...)

- got rid of $Id$'s (for the moment, at least).  in other
  words, there should be no more "empty" checkins.

- internal: some minor cleanups.

- removed some hacks that worked around 1.6 alpha bugs
- removed bogus test code from sre_parse

This one should work with unicode expressions, and compile
a bit more silently.

   untabifies the files.  No actual code changes were made.

NOTE: THIS IS VERY ROUGH ALPHA CODE!