void gweather_info_store_cache ( void )
Ensures that any data cached from the network is stored to disk.
Calling this is not necessary, as the cache will be saved when
the last reference to a
GWeatherInfo will be dropped.
On the other hand, it must be called if there is any chance that
the application will be closed without unreffing all objects, such
as when using a language binding that employs a GC.