public.
* Removed the non-signal conditions from __all__.
* Removed the XXX comment which was resolved.
* Use ^ instead of operator.xor
* Remove the threading lock which is no longer necessary.

* Map conditions to related signals.
* Make contexts unhashable.
* Eliminate used "default" attribute in exception definitions.
* Eliminate the _filterfunc in favor of a straight list.

Docs:
* Eliminate documented references to conditions that are not signals.
* Eliminate parenthetical notes such as "1/0 --> Inf" which are no
  longer true with the new defaults.

* add more __init__ tests

* use assertions instead of tests after internal calls that can't fail.
* expand test coverage

c.l.py

methods on string and unicode objects. Added unicode.decode()
which was missing for no apparent reason.

first day of the week.

[ 987287 ] Python 2.4a1, interpreter hanging on Keyboard Interrupt

couple of these are currently found in index data, but these should
all be handled in the same way.

Closes SF bug #952737.

Need to return -1 on error.

Needs backport.

isn't always set to an integer value when it's defined.

[ 960406 ] unblock signals in threads

although the changes do not correspond exactly to any patch attached to
that report.

Non-main threads no longer have all signals masked.

A different interface to readline is used.

The handling of signals inside calls to PyOS_Readline is now rather
different.

These changes are all a bit scary!  Review and cross-platform testing
much appreciated.