[Infobot module] Add <alias>

[pgengler]

An <alias> token should be added to the Infobot bot module for marking a phrase as an alias of another. This would be similar to the existing <feedback> token but instead of running the text through the entire bot processing chain this would just look up the text in the Infobot flow as if it were the original message. (Naturally this will also need a limit to the number of times it will follow an alias, to avoid problems with long chains or circular aliases.)