Option to not phone home at startup (add “do not check for updates” as an opt out)

[illwieckz]

When the desktop file did not launched the updater but the game, people not wanting to phone home just had to click the Unvanquished icon and not run the updater. Now that that Unvanquished icon runs the updater (something I vote for), we need an option to skip the check at startup and just run the game straight. Players would just have to click the gear button to re-enable the update check if needed.

This would not only please privacy-caring people but also those who may play on disconnected networks (see #35).

[slipher]

The updater already works optimally on disconnected networks.

Note that it is impossible to do an updater update if you click the gear button.

The appeal of running without pinging unvanquished.net seems rather niche, since that is also required to use the server list. Those brave few could consider making a shortcut directly to daemon, or setting up a blackhole DNS entry...

[illwieckz]

I just noticed that implementing the single-url download bootstrap (#46, #78) may makes this easier to implement.

Of course, until such option is implemented, users can just run the daemon binary directly, and we can tell them to do so if they are concerned by this.