Make sure users don't downgrade

[poma]

When user thinks that setup.exe is uploader and runs it every time it will prevent automatic updates as setup will always downgrade app before launching it. Need to prevent this behavior.

[martijnhoekstra]

It's not clear squirrel will support this anytime soon/ever (while there is a PR addressing the issue at Squirrel/Squirrel.Windows#926, the future of squirrel itself is unclear per Squirrel/Squirrel.Windows#1470).

Any fix will be a big project, which may require moving away from squirrel (but to what is unclear). A launcher/application switch where the launcher is clobbered by setup.exe, but downloads the latest application sounds feasible, but the complexity may be difficult to justify.