Add missing virtual destructor for Timer::Callback (abstract) class

common/include/lima/Timer.h

@@ -38,6 +38,8 @@ namespace lima
     enum Stat {DOWN,DELAY,UP,RISING_EDGE,FALLING_EDGE};
     class Callback
     {
+    public:
+      virtual ~Callback() {}
     protected:
       virtual void start() {}
       virtual void risingEdge() {}

common/sip/Timer.sip

@@ -31,6 +31,8 @@ public:
   enum Stat {DOWN,UP,RISING_EDGE,FALLING_EDGE};
   class Callback
   {
+  public:
+    virtual ~Callback();
   protected:
     virtual void start();
     virtual void risingEdge();