Fix printing of argparse help to go to stdout by default.
Fix printing of argparse help to go to stdout by default.

Our help message was tricky to page because it went to stderr (argparse
default, which I don't particularly like).

Also fixed encoding marker, which was incorrect.  The problem exists in other
files too, the right syntax is:

# coding: utf-8

(with 'coding', not 'encoding').  See http://www.python.org/dev/peps/pep-0263

ipython/ipython,ipython/ipython