Export the COM entry point functions.

Note that there are several conflicting base addresses defined for
other extensions, also not all are listed in dllbase_nt.txt.

obviously overlaps w/ datetime (but may -- no time for more here now).

to others to argue about how to build it on other platforms (on Windows
it's in its own DLL).

CAUTION:  The Python test still has many failures, but I'm out of time
for this now (already took much longer than hoped to get this far).
The base bz2 library does pass its own tests (see next).

CAUTION:  People building on Windows have to download and build tne
bz2 compression libraries now.  See PCbuild\readme.txt for complete
instructions.

* Base address for all extension modules updated. PC\dllbase_nt.txt
also updated.  Erroneous "libpath" directory removed for all
projects.

* winsound module moved from a builtin module to an extension
module.  This was done primarily to avoid Python16.dll needing to
pull in winmm.dll.  Really dumb test added for winsound - but if
nothing else it ensures the module imports.

added notes to readme.txt about NumPy targets;
added some symbols to python_nt.def.