Add main menu warning if outdated or errored mods detected

[Falki-git]

• Show yellow triangle next to "Mods" if SW detects at least one outdated mod
• Add settings config if warning should be displayed, defaults to true

Solves https://github.com/SpaceWarpDev/SpaceWarp/issues/214

[Falki-git]

Added red triangle if errored mods detected. Red trumps yellow.