Bump to Python v. 3.3 in documentation reference
Updated calendar documentation

- Added the comparison operators section.
- Added the ISO calendar.
- Changed convention for weekdays (now Monday is 1 and Sunday is 7).
- Added description of exception in gregorian replace.
- Removed gregorian.week_and_day, which was of small usage and difficult to understand. Added in its place the week_number method.
- General clean-up in method definitions.
Reformat gregorian calendar tests to new numbering scheme

0nn - test constructors
1nn - attributes
2nn - static and class methods
3nn - operators and built-in (e.g. hash, bool)
4nn - other methods
5nn - representations
9nn - pickling, subclassing and other
Test suite completed

- Added INF, NAN and 1 + 1j to a few invalid type test data.
- Modified Gregorian test data for new weekday convention (i.e. Monday = 1, Sunday = 7).
- Modified invalid test data with a more generic year number, and added a test for an invalid month.
- Removed eq_gregorian, because GregorianCalendar now has comparison operators.
- Added a few test: creation from attributes, comparison operators, hash equality, repr, str, pickling and subclass.
- Added other invalid conditions for replace
Test suite fixed

- I was wrong in correcting all weekday numbers: only Sunday had to be changed as it is now
- Removed two 'not' that were left from last editing
- Changed tests methods for repr and str so that they do not use the same technique as the code they tests
Completed GregorianCalendar class

- Fixed weekday so that it returns 7 for Sunday (before it returned 0)
- Added:
  - the comparison operators
  - __hash__
  - __repr__
  - __str__