nroff: Fix style of names.

nroff: Fix style of names.

The recommended Google Python style is multi_word_names, not
multiWordNames.

There are lots of other places where the style could be improved.
I started here because I was working in this code anyway and because
this code is only used at build time and not installed, so that it
can't break any third-party code.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Justin Pettit <jpettit@nicira.com>