XBMCTinyXML: refactoring: fully remove CStdString
TinyXML::Parse: refactoring: generate RegExp only when needed, use search for char instead search for string, const ref param allow to call function directly, without re-copying data to new string
XBMCTinyXML::Parse: refactoring: remove unused parameter; call function with std::string (without .c_str())
XBMCTinyXML::Parse: remove uppercase from RegExp (matching is already caseless)