fix #3185: NPE in GeoDirHandler

One must not unconditionnally update geolocation and direction data as
it may be null.

This is a more correct fix for #2717.
fix #3186: do not try to install a null map source

If the wanted map source can no longer be found (because it has been
made unavaiable on the device), try to install a default one, or
fail silently with an error message in the log.
Merge branch 'release' into upstream
Merge branch 'issue-3186' into upstream