Return as soon as we have a port for the current hostname

[RealOrangeOne]

Rather than once all are enumerated. Enumerating processes is pretty fast anyway, but the faster we can make it the better!

(Has a bit of an impact on #17, as this blocks all requests until it's finished)

This should be tested on macOS, as it might do strange things there (hence the base except). Works fine for me!

I've also added support for specifying multiple hostnames, a niche but potentially really useful change.