i18n: encode output in user's local encoding
This makes the translated output obey the HGENCODING environment
variable or the preferred encoding as set by the LANG or LC_ALL
environment variables.
Python 2.4 has a lgettext method which is similar, except that it
doesn't know about HGENCODING or the settings in .hgrc.
% basic
% unknown
*** [alias] unknown: command bargle is unknown
% ambiguous
*** [alias] ambiguous: command s is ambiguous
% recursive
*** [alias] recursive: circular dependency on recursive
adding foo
% with opts
C foo