Instead of generating the list of message ids anew during every build,
the file is generated manually and committed into the
repository. Also, the list of defines is stored in id128-defines.h,
also kept in the repository. Both files should only grow.

This should make build easier. But it also fixes a problem with
systemd, which occasionally drops message definitions. We will keep
them forever, so it should be safe to rely on the presence of message
definitions which systemd does not use anymore.

Fixes #23.

journald.send() is renamed to journald.sendv(), and a replacement
journald.send() is added. This new function has a more pythonic API,
where one positional argument is used for the message, and keyword
arguments can be used to specify other fields.

Implementing argument parsing in C would be really painful, for little
gain, so a pure-python module is added, which provides send(), which
in turn calls sendv().

Should work with Python 3.0 - 3.2. Compatibility with Python 3.3 might
require additional changes.