Prevent players from switching teams

Signed-off-by: Lixfel <agga-games@gmx.de>

FightSystem_Core/src/de/steamwar/fightsystem/commands/GUI.java

@@ -61,8 +61,10 @@ public class GUI {
         }
 
         SWInventory inv = new SWInventory(p, 9, msg.parse("JOIN_REQUEST_TITLE", p));
-        addTeamRequest(p, inv, 0, Fight.getBlueTeam());
-        addTeamRequest(p, inv, 8, Fight.getRedTeam());
+        if(!Fight.getRedTeam().isPlayerInTeam(p))
+            addTeamRequest(p, inv, 0, Fight.getBlueTeam());
+        if(!Fight.getBlueTeam().isPlayerInTeam(p))
+            addTeamRequest(p, inv, 8, Fight.getRedTeam());
         inv.open();
     }