When connecting again, no data is cleared. Since we now keep
track of event IDs and not just timestamps it makes sense to not
forget what the last event IDs were. To still run into the
"limit" case the flags for having events at all can be used
(which is also reset on just `connect()`).
I have observed that Syncthing Tray can get stuck thinking a remote device
still needs data. Likely the update got lost. The code contains certain
conditions in which folder completion events and requesting completion are
supressed. Those conditions are based on timestamps. That is not ideal as
the accuracy is only one second (so different timestamps might be
considered equal as they are rounded to be the same). Additionally, it
makes no sense to assume a timestamp upon receiving a response as the
information might be older than the time it was received.
This change avoids those conditions. It rather uses the event ID to
decide what event/reply is newer.
This change also uses quint64 instead of int for event IDs to avoid running
into an overflow (or rather conversion error) when deserializing the ID
which might be bigger than int. (Not sure how big the ID can become; this
is to be on the safe side.)
Martchus