Add support for angry bees.

This commit introduces a new type variant, `angry-bee`, which is a bee
whose anger level is maximized upon spawning, much in the same vein as
its angry wolf cousin.

Note that bees are not available prior to Minecraft 1.15, so a sentinel
`null` name is used in the registration to prevent warnings from being
logged on server versions that don't have a concept of bees.

Closes #584

src/main/java/com/garbagemule/MobArena/waves/MACreature.java

@@ -7,6 +7,7 @@ import org.bukkit.DyeColor;
 import org.bukkit.Location;
 import org.bukkit.Material;
 import org.bukkit.World;
+import org.bukkit.entity.Bee;
 import org.bukkit.entity.Creature;
 import org.bukkit.entity.Creeper;
 import org.bukkit.entity.EntityType;
@@ -101,6 +102,9 @@ public class MACreature {
             case "poweredcreeper":
                 ((Creeper) e).setPowered(true);
                 break;
+            case "angrybee":
+                ((Bee) e).setAnger(Integer.MAX_VALUE);
+                break;
             case "angrywolf":
                 ((Wolf) e).setAngry(true);
                 break;
@@ -232,6 +236,7 @@ public class MACreature {
         // spawn time. For example, "angry-wolf" is just a normal wolf with
         // its anger property is set to true.
         //
+        put("angrybee", "angrybees", "BEE", null);
         put("angrywolf", "angrywolves", "WOLF");
         put("babyzombie", "babyzombies", "ZOMBIE");
         put("babyzombievillager", "babyzombievillagers", "ZOMBIE_VILLAGER");