mod_cron: Initial commit of periodic task runner A number of modules now have periodic tasks that need to run, e.g. for cleaning out old messages or files. This has highlighted a need for coordinating and optimizing scheduling of such tasks.

-- Only the operators needed by net.websocket.frames are provided at this point
return {
	band   = function (a, b) return a & b end;
	bor    = function (a, b) return a | b end;
	bxor   = function (a, b) return a ~ b end;
};