doctest version of TestSimpleDateTimes

[Alexis]

Hi,

I've written a doctest version of TestSimpleDateTimes. It reproduces
all the original tests, except for testDays(), because I couldn't
understand what that test did.

As a doctest, it also serves as a kidn of explanatory documentation.
Please check it out. It's at http://www.alexisgallagher.com/simpledatetimes.txt

In the course of writing this, I was puzzled to discover that, in
Calendar.parse(), the optional argument sourceTime is ignored
completely when parsing dates. In other words, the time information in
sourceTime is always ignored. Is this intended? It seems a bit
inconsistent.

ciao,
alexis