Load all biomes for data packs, not just thought used ones

src/main/java/com/volmit/iris/engine/parallel/MultiBurst.java

@@ -35,7 +35,7 @@ public class MultiBurst {
     }
 
     public MultiBurst(String name, int priority, int tc) {
-        service = Executors.newFixedThreadPool(tc, r -> {
+        service = Executors.newFixedThreadPool(Math.max(tc, 1), r -> {
             tid++;
             Thread t = new Thread(r);
             t.setName(name + " " + tid);