A small and boring technical update.

- [misc] Improved safe_mode to handle more cases.
- [misc] The game auto switches to safe_mode when it encounters more serious problems.

- [removed] Removed ingame changelogs (too troublesome to update and looks ugly on the interface, besides it was redundant since players can read Steam/website announcements anyway).

- [fix] Fixed safe_mode (a bug preventing it from working in some cases).