Removed definition of URL for "qt" namespace from individual parts of the model, and instead define it once at the top. This is the way that Bob's tools generate a v3 sys defn, and it brings the auto generated one in sync with the one usable in the build. Also added a v3 system definition for S^4, although it's not quite in sync with the v2 sys defn there (because that's not in sync with the generated sys defns at the moment).

Add auto generated symbian4 system model (packages@ed48b86c3e24)