%open, %close for files, %open_group, %close_group for groups

%open, %close for files--the older %initialize, %finalize continue to work.
%open_group, %close_group for groups now.

Added a destructor finalization method that automatically flushes data to disk and closes file when leaving procedure scope. This helps avoid data corruption if user forgets to %close().

updated to zlib 2.0.4