Fixes to P2P multiplayer

I finally got around to test the online multiplayer feature aaaaand is broken.

But after an hour and two router restarts i finally figured it out. I was using the wrong IP address when trying to join another game. Fixed! And more, in order to remove some unpleasant parts from connection phase, i improved the interface with more useful logs (available IP addresses for example).

Other minor improvements were made in consequence with a small playtest session i hosted.

I really do hope no other problems with arise on this side of the game code. Although, i kind of started to like all this thinking in remote function calls. It's truly a great system. Cheers to all Godot contributors!