[Datetime Concept]: Booking Up for Beauty Exercise

[colinleach]

Incomplete draft for discussion. This is a fairly direct port from C#.

Is this suitable for the datetime concept? Usual options:

• Use with minor tweaks.
• Use after substantial revision.
• Scrap it and think of something better.

Some things I'm unhappy about:

• It's all datetime.datetime, nothing much about time or date
• Task 2 is locale-specific. It works for me (in the US) and should be OK on the test runner, but will fail for non-English locales. The test file could set the locale to EN-US, but I'm reluctant to mess with users' machine settings unless I'm very confident of restoring it at the end of the test.
• Task 6 is really lame.