Fix for a crash occurring when the window is resized.

Temporary Platform objects were registering themselves.
The move ctor would then initialize the final object in
the circular buffer (see PlatformSystem), but it would
leave the address of the temporary object registered in
the ObserversManager.

src/observersmanager.hpp

@@ -96,6 +96,7 @@ namespace cloonel {
 
 		TicketType Add ( T parObserver );
 		void Remove ( TicketType parTicket ) noexcept;
+		void Update ( TicketType parTicket, T parObserver );
 		std::size_t size ( void ) const { return m_usedCount; }
 		iterator begin ( void ) { return iterator(m_occupied, m_list, false); }
 		iterator end ( void ) { return iterator(m_occupied, m_list, true); }
@@ -148,6 +149,18 @@ namespace cloonel {
 			m_list.resize(newSize);
 		}
 	}
+
+	///--------------------------------------------------------------------------
+	///--------------------------------------------------------------------------
+	template <typename T>
+	void ObserversManager<T>::Update (TicketType parTicket, T parObserver) {
+		assert(static_cast<std::size_t>(parTicket) <= m_list.size());
+		assert(m_occupied[parTicket - 1]);
+		assert(m_usedCount > 0);
+		assert(m_list.size() == m_occupied.size());
+
+		std::swap(m_list[parTicket - 1], parObserver);
+	}
 } //namespace cloonel
 
 #endif