added __all__ lists to a number of Python modules

added test script and expected output file as well
this closes patch 103297.
__all__ attributes will be added to other modules without first submitting
a patch, just adding the necessary line to the test script to verify
more-or-less correct implementation.

Lib/chunk.py

@@ -48,6 +48,8 @@ specifies whether or not chunks are aligned on 2-byte boundaries.  The
 default is 1, i.e. aligned.
 """
 
+__all__ = ["Chunk"]
+           
 class Chunk:
     def __init__(self, file, align = 1, bigendian = 1, inclheader = 0):
         import struct