per mule's patch, added support for a round robin across multiple outproxies

instead of the standard 'httpclient 4444' or 'httpclient 4444 squid.i2p', you can now specify a comma delimited list of outproxies:
'httpclient 4444 squid.i2p,www1.squid.i2p,www2.squid.i2p' and each individual http request goes through a randomly selected proxy
there are a few general issues with this, such as a lack of affinity (web applications that require a session to always come from a single IP address will break)
but it should work most of the time.