Added the possibility to not use a max level for Fishing

by using a negative number, changed default
treasure.yml file accordingly

src/main/java/com/gmail/nossr50/config/TreasuresConfig.java

@@ -131,10 +131,8 @@ public class TreasuresConfig extends ConfigLoader{
                 }
 
                 int maxLevel = config.getInt("Treasures." + treasureName + ".Max_Level");
-
-                if (maxLevel < 0) {
-                    reason.add("Invalid Max_Level: " + maxLevel);
-                }
+
+
 
                 if (noErrorsInTreasure(reason)) {
                     FishingTreasure fTreasure = new FishingTreasure(item, xp, dropChance, dropLevel, maxLevel);