python3 compat: 2to3: `except E as e:` syntax

First step to Python 3 compatibility
"2to3 -w -f except ." See [1]

[1] http://docs.python.org/2/library/2to3.html#fixers
python3 compat: print() function syntax
python3 compat: remove lots of Python 2.5 and earlier dependent code; use print() function syntax
python3 compat: `raise E(arg)` syntax

.with_traceback() is not backward compatible, so left to on-demand 2to3 run