Enable main player and admin command declaration

See https://github.com/BentoBoxWorld/BentoBox/issues/448

src/main/java/world/bentobox/bentobox/api/addons/GameModeAddon.java

@@ -1,8 +1,11 @@
 package world.bentobox.bentobox.api.addons;
 
+import java.util.Optional;
+
 import org.bukkit.Location;
 import org.bukkit.World;
 
+import world.bentobox.bentobox.api.commands.CompositeCommand;
 import world.bentobox.bentobox.api.configuration.WorldSettings;
 import world.bentobox.bentobox.util.Util;
 
@@ -17,6 +20,14 @@ public abstract class GameModeAddon extends Addon {
     protected World islandWorld;
     protected World netherWorld;
     protected World endWorld;
+    /**
+     * Main player command. Addons can use this hook to into this command.
+     */
+    protected CompositeCommand playerCommand;
+    /**
+     * Main admin command. Addons can use this hook to into this command.
+     */
+    protected CompositeCommand adminCommand;
 
     /**
      * Make the worlds for this GameMode in this method. BentoBox will call it
@@ -61,5 +72,17 @@ public abstract class GameModeAddon extends Addon {
         return endWorld;
     }
 
+    /**
+     * @return the main player command for this Game Mode Addon
+     */
+    public Optional<CompositeCommand> getPlayerCommand() {
+        return Optional.ofNullable(playerCommand);
+    }
 
+    /**
+     * @return the main admin command for this Game Mode Addon
+     */
+    public Optional<CompositeCommand> getAdminCommand() {
+        return Optional.ofNullable(adminCommand);
+    }
 }

src/main/java/world/bentobox/bentobox/managers/AddonsManager.java

@@ -239,6 +239,18 @@ public class AddonsManager {
         return addons;
     }
 
+    /**
+     * @return List of enabled game mode addons
+     * @since 1.1
+     */
+    public List<GameModeAddon> getGameModeAddons() {
+        return addons.stream()
+                .filter(addon -> addon.getState().equals(Addon.State.ENABLED))
+                .filter(GameModeAddon.class::isInstance)
+                .map(GameModeAddon.class::cast)
+                .collect(Collectors.toList());
+    }
+
     /**
      * Gets the list of Addons that are loaded.
      * @return list of loaded Addons.