CamelIMAPXStore: Try harder to track settings.
CamelIMAPXStore: Try harder to track settings.

Connect a "notify" signal handler to a newly-installed CamelSettings
instance, and emit a "folder-info-stale" signal for certain settings
changes that would ordinarily require an application restart.

Specifically, listen for changes to:

    "use-real-junk-path"
    "use-real-trash-path"
    "use-subscriptions"

matzipan/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server,Distrotech/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server,tintou/evolution-data-server,Distrotech/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server,tintou/evolution-data-server,Distrotech/evolution-data-server,Distrotech/evolution-data-server,Distrotech/evolution-data-server