- Modified Record::get* methods to be const.
- Implemented TDB2::add.
- Renamed Task::valid to Task::validate.
- Implemented Task::setEntry to default creation time.
- Fixed bug where TDB2 was opening files "rw" instead of "r+".
- Renamed T2.h -> Task.h, T2.cpp -> Task.cpp. This permanently avoids
the problem where g++ on OpenBSD 4.5 fails because of the T class,
which probably conflicts with C++ templates. Who knows.