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)
Even empty QRegExp can occupy a lot of space in memory, which can
grow into a big number with tens of thousands AdBlock rules.
QRegExp is now allocated with new, and only when really needed.
It now also supports Windows 8 detection.
Function have been renamed from buildSystem to operatingSystem
as it does not really returns build system anymore.
