[C++-SIG] CXX-a3

[Paul F. Dubois]

CXX-a3.zip and .exe are at ftp-icf.llnl.gov/pub/python.

Changed namespace name to Py to match work being done by Furnish.

Changed PythonExtension<T>::methods() to api() and added a new methods() to
hold a method table for additional, non-api methods.

Added new methods to the Demo/ "r" object and R class, and excercised the
new facilities in rtest.cxx.

Misc. small improvements.