[Poshuku CW] Don't check for orig string emptiness on elem hiding.
[Poshuku CW] Don't save original strings at all.

Saves around 7 MiB of memory on EasyList + EasyPrivacy + RuAdList.
[Poshuku CW] Consider case for plain matches.
[Poshuku CW] Store pattern/case sensitivity in the PCRE wrapper.

Allows to save up memory a bit for the empty objects.
[Poshuku CW] Avoid QByteArrayMatcher.

It eats over 1 KiB per object.

Save around 80 MiB on EasyList + EasyPrivacy + RuAdList.