Fixed editor brokenness.

# More useful environment (water, lighting) editing
(now saved into the map files).
Fixed no-PCH a bit.

This was SVN commit r4002.

source/tools/atlas/AtlasUI/General/Observable.h

@@ -43,6 +43,12 @@ public:
 		}
 	}
 
+	Observable<T>* operator=(const T& rhs)
+	{
+		*dynamic_cast<T*>(this) = rhs;
+		return this;
+	}
+
 private:
  	boost::signal<void (const T&)> m_Signal;
 };