Comply with PEP 3310 "Catching Exceptions in Python 3000"

Generated with `2to3 -f except`.

Signed-off-by: Christophe Vu-Brugier <cvubrugier@yahoo.fr>
Fix whitespace in comma separated items

Generated with `2to3 -f ws_comma`.

Signed-off-by: Christophe Vu-Brugier <cvubrugier@yahoo.fr>
Replace execfile() with exec() since it does not work with Python 3

Signed-off-by: Christophe Vu-Brugier <cvubrugier@yahoo.fr>
Replace filter() with list comprehensions

Generated with `2to3 -f filter`.

Signed-off-by: Christophe Vu-Brugier <cvubrugier@yahoo.fr>
Merge pull request #24 from cvubrugier/2to3

2to3: preparatory work for python 3