Lazy-initialize the network information backend so warnings it possibly
shows don't disturb the output of the CLI (which does not need the network
information backend anyway).
* Allow to pause all devices on metered network connections (devices will
be automatically resumed when network is no longer metered)
* Allow to stop Syncthing when it was started via the built-in launcher
on metered network connections (it will be automatically started again
when the network connection is no longer metered)
* See https://github.com/Martchus/syncthingtray/issues/231
Don't go though the list of dirs/devs for every dir/dev change event. Just
go though the list once after receiving new events. This makes also the
code a little bit easier to follow.
Apparently this is still problematic leading to errors like
`Qualifying with unknown namespace/class`. It seems that moving the enum to
a different header file works. The trick to use a macro to define
`enum class` ceased to work on the other hand.
Specifying a function with the namespace like
`void QtGui::FinalWizardPage::showResults()` leads to the same problem and
also needs to be avoided.
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