Refactor spawn reporting (#1519)

Not all that could be done for now

src/main/java/carpet/CarpetServer.java

@@ -87,7 +87,7 @@ public class CarpetServer // static for now - easier to handle all around the co
     {
         CarpetServer.minecraft_server = server;
         // shoudl not be needed - that bit needs refactoring, but not now.
-        SpawnReporter.reset_spawn_stats(server, true);
+        SpawnReporter.resetSpawnStats(server, true);
 
         forEachManager(sm -> sm.attachServer(server));
         extensions.forEach(e -> e.onServerLoaded(server));