RegExp: check PCRE for real JIT support and prepare to support studying of expression
RegExp::GetReplaceString: rewrote
* fix use of unallocated memory with not matched result
* support "\10"-"\20"
* wider use std::string
RegExp: support PCRE study of expressions
CRegExp::GetReplaceString: optimization
RegExp: add ctor doxy
RegExp: add doxy for RegComp
RegExp::RegFind: refactoring
* store and use only needed part of subject string
* allow to specify number of characters to test
* check for invalid startoffset values
* unsigned type for startoffset
RegExp::RegFind: add doxy
CRegExp::RegComp: support JIT
CRegExp::RegFind: support JIT