Fix warnings from gcc 4.0 by providing virtual destructor.

src/generic_event.cpp

@@ -15,12 +15,15 @@
 #include <algorithm>
 
 namespace events{
+	observer::~observer() {
+	}
 	generic_event::generic_event(std::string name){
 		name_ = name;
 		change_handler_ = false;
 		notify_active_ = false;
 	}
-
+	generic_event::~generic_event() {
+	}
 	bool generic_event::attach_handler(observer* obs){
 		bool handler_attached = false;
 

src/generic_event.hpp

@@ -34,6 +34,7 @@ namespace events{
 	class observer{
 	public:
 		virtual void handle_generic_event(const std::string& event_name) = 0;
+		virtual ~observer();
 	};
 
 	/*
@@ -42,7 +43,7 @@ namespace events{
 	class generic_event{
 	public:
 		generic_event(std::string name);
-
+		virtual ~generic_event();
 		virtual bool attach_handler(observer* obs);
 		virtual bool detach_handler(observer* obs);
 		virtual void notify_observers();