fix warnings and some reloading issues

modules/game_battle/battle.lua

@@ -81,11 +81,15 @@ function Battle.terminate()
   battleButton = nil
   battleWindow:destroy()
   battleWindow = nil
+  mouseWidget:destroy()
+  mouseWidget = nil
 
   disconnect(Creature, {  onSkullChange = Battle.checkCreatureSkull,
                           onEmblemChange = Battle.checkCreatureEmblem } )
 
   disconnect(g_game, {    onAttackingCreatureChange = Battle.onAttack } )
+
+  Battle = nil
 end
 
 function Battle.toggle()

modules/game_battle/battle.otmod

@@ -5,10 +5,13 @@ Module
   website: https://github.com/edubart/otclient
   icon: battle.png
 
+  dependencies:
+    - game
+
   @onLoad: |
     dofile 'battle'
     Battle.init()
 
-  @onUnload:
+  @onUnload: |
     Battle.terminate()