Added support for reading a .osg style data from a file string when trailed by a .osgs extension i.e.

osgviewer "osgTerrain::Terrain { ElevationLayer { CartesianLocator 0 0 1000000 1000000 Image ps_height_512.tif } ColorLayer { CartesianLocator 0 0 1000000 1000000 Image ps_texture_1k.tif } }".osgs

src/osgDB/Registry.cpp

@@ -169,6 +169,7 @@ Registry::Registry()
     #endif
     }
 
+    addFileExtensionAlias("osgs", "osg");
     addFileExtensionAlias("shadow",  "osgShadow");
     addFileExtensionAlias("terrain", "osgTerrain");
     addFileExtensionAlias("view",  "osgViewer");