This filter can be used to implement a reverse proxy; similar to the
apache ProxyPass and ProxyPassReverse directives.  Rules are stored in
a text file with one rule per line.  Each line consists of a rule
name, whitespace, regular expression, whitespace, and a substitution
pattern.  Example rules:

    PASS ^http://proxyservername:51966/(.*) http://www.foo.com/$1 
    REVERSE ^http://www.foo.com/(.*) http://proxyservername:51966/$1 
 
User preferences:

* Translate.rules

  Location of the translate rules file.  The default is ~/Muffin/translate.
