pause_when_empty should by default be true, it is the default and intended behavior for 99% of servers, along with that, most players(myself included), expect that default configs will match the standard default of the game, and this caught me off guard to see the game was still running.
resolves#215
Adds caves support.
Adds default configs for master and cave servers.
Adds a default cluster config.
Adds worldgen files to generate caves and an overworld.
