Added support for extending models in packages.
Added support for extending models in packages.

jlhughes/foam,jacksonic/foam,foam-framework/foam,foam-framework/foam,osric-the-knight/foam,jlhughes/foam,mdittmer/foam,foam-framework/foam,mdittmer/foam,foam-framework/foam,mdittmer/foam,jlhughes/foam,jlhughes/foam,foam-framework/foam,osric-the-knight/foam,jacksonic/foam,jacksonic/foam,osric-the-knight/foam,jacksonic/foam,osric-the-knight/foam,mdittmer/foam