notInstalledHint, requiresUpdateHint and updatePendingHint are missing

[MJRamon]

These lang lines are not ever shown and are missing in the code entirely.

Thus, a player cannot know, if modpack is installed or there's an update.

[hedgehog1029]

These used to be used but were dropped in d6e7c02 due to some kind of bug. I'll check in with sk89q because it's possible this was a Java bug that was resolved...