RegExp: prepare to support PCRE study, check PCRE for real JIT support
RegExp::RegComp: support PCRE study of expressions and JIT compile
RegExp::RegComp: add doxy
RegExp::RegFind: support JIT
Merge pull request #3442 from Karlson2k/regexp_rework_04a

RegExp rework - part 04
[GUI] Fades control textures if control is disabled