Add switches to turn off format support warnings

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Delayed autosave of configuration

And remove obsolete save() method.

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Change signature and name of config_changed signal

To match Diorite.KeyValueStorage.

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Use interface Diorite.KeyValueStorage

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>