todo list

- Write methods cacheAllExifTags() and cacheAllIptcTags() that will read and cache all the tag values (to be used in a separate threads, for applications that need to access all the tags anyway)
- Rewrite the exiv2 command-line tool and the test binaries in Python and (Python) scripts to run the same tests that are run to test exiv2
- Rewrite the docstring documentation of the module using epydoc's syntax (http://epydoc.sourceforge.net/manual-fields.html)
- Write a complete documentation for the binding and it uses
- Write unit tests (http://docs.python.org/lib/module-unittest.html)
- Use pkgconfig with scons in order to check the dependencies before compiling (http://www.scons.org/wiki/UsingPkgConfig)