Moved SimpleViewer and GraphicsWindow into their own osgViewer library, updated simpleviewer examples to reflect this change

src/osgViewer/Version.cpp

@@ -0,0 +1,12 @@
+#include <osgGA/Version>
+
+const char* osgGAGetVersion()
+{
+    return "1.2";
+}
+
+
+const char* osgGAGetLibraryName()
+{
+    return "OpenSceneGraph Gui Adapter Library";
+}