Add option to disable use of local net

[Ilya87]

Is your feature request related to a problem? Please describe.
I need to use Zerotier on a daily basis, and i need it to work always. My host PC I use to translate from (my remote game server) has external ip, no NAT. This ip address already setup in Moonlight, but with ZeroTier turned on, Moonlight use Zerotier ip. As zerotier is less stable than direct ip connection and use udp, the connection quality and response became worse.

Describe the solution you'd like
Add an option to disable local net use.

[cgutman]

If you uncheck the checkbox in settings called "Automatically find PCs on the local network" and then delete and re-add your PC using the external IP address, I think it should do what you want.