Regexp will be parsed into parts that can be used with
QString::contains for quick match. If url contains all parts,
real QRegExp matching is applied.
This speedup affects rules that are internally converted into
regexp, not AdBlock's regexp rules (but those rules are very rarely used
in subscriptions, so there's no need to optimise them)
Twitter uses multiple same forms (differing in class and id names).
Now PageFormComplter also tests occurence of username name=value pair
in sent post data.
