default constructor for rlib::string, sio can send std::string directly, sio::sendn doesn't return value now

update log.hpp, to support formatstring in logger.log, to avoid eval unnecessary arguments runtime(Ex. rlog.debug("{}"_format(ExpensiveThing) => rlog.debug("{}", ExpensiveThing))).

add a workaround for intelc compilation issue. fix intelc detector. comment out unfinished code in functional.hpp