EXT-6114: Ignore secondlife:///app/login SLapps if logged in.
EXT-6114: Ignore secondlife:///app/login SLapps if logged in.

If you were already logged in, clicking on these SLapps would crash
your viewer (crash was in experimental reg-in-client code). We now
ignore these SLapps if the user is already logged in, and a one-time
warning is emitted in this case.

gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm