Small bug fixes & improved multiplayer stability

- Added a 3 mins per turn timer in multiplayer.
- Fixed various causes of multiplayer desyncs.
- Added new sounds when your multiplayer game is starting (so you don't miss it).
- Fixed multiplayer lobby text overlapping in some languages.
- Turned off Invasion until we can fix it properly.
- Atlantis will now only spawn when it can be completed.
- Added some opportunities to the backup category (you can see them a second time in the late game).
- Fixed a rare blocker in the tutorial, if you complete an opportunity and cannot chose the reward.
- Fixed 1/2/3/4/5 keyboard shortcuts showing as Num1/Num2/etc in Settings (numpad still works tho).
- Fix for an untranslated string on demo's load game screen.
- Fix for unlock maps button in demo going blurry for a second on first hover.