The upload date was being updated regardless if the new one had more
precision or not, this caused items on the feed to jump around when the
user opened one of them.
This changes it to only update when the existent upload date is null or
the new one has a higher precision (i.e. is not an approximation).
Now only the subscriptions from the selected group by the user will be
loaded.
Also add an option to decide how much time have to pass since the last
refresh before the subscription is deemed as not up to date. This helps
when a subscription appear in multiple groups, since updating in one
will not require to be fetched again in the others.
Stypox
Isira Seneviratne
wb9688
Mauricio Colli