Lots of code reorganization with a few small API changes.

Lots of code reorganization with a few small API changes.

Change all the local names that start with SSL to start with PySSL.
The OpenSSL library defines lots of calls that start with "SSL_".  The
calls for Python's SSL objects also started with "SSL_".  This choice
made it really confusing to figure out which calls were to the library
and which calls were local to the file.

Add PySSL_SetError() that sets an exception based on the information
from SSL_get_error().  This function will eventually replace all the
calls that set it with an error message that is based on the name of
the call that failed rather than the reason it failed.  (Example: If
SSL_connect() failed it used to report "SSL_connect error" now it will
offer a specific message about why SSL_connect failed.)

    XXX It might be helpful to augment the error message generated
    below with the name of the SSL function that generated the error.
    I expect it's obvious most of the time.

Remove several unnecessary INCREFs in the module's constructor call.
PyDict_SetItem() and friends do the INCREF for you.