A simple rust library to get a free local port or to check if a port somewhere is reachable
Example: ```rust
// get a free local port let freeport = portcheck::freelocalport();
// get a free local port between 10000 and 15000 let freeportinrange = portcheck::freelocalportinrange(10000, 15000);
// check whether a remote port is reachable let isreachable = portcheck::isportreachable("192.0.2.0:8080"); // or let isreachable = isportreachablewithtimeout("192.0.2.0:8080", Duration::frommillis(10_000));
```