Converted the Carbon modules to use PEP252-style objects, with

Converted the Carbon modules to use PEP252-style objects, with
descriptors in stead of manual getattr hooks to get at attributes
of the objects.

For Qd I have in stead gotten rid of most of the attribute access
in favor of the carbon-style accessor methods (with the exception
of visRgn, to be done later), and of the Carbon.Qd.qd global object,
for which accessor functions are also available.

For List I have fixed the fact that various methods were incorrectly
generated as functions.

CF is untouched: PEP252 doesn't allow "poor-mans-inheritance" with
basechain, so it will have to wait for PEP253 support.