Better multiplayer game screen - all 'game settings' are accessible immediately without a subscreen!

Solved some problems with resigning - we have others, specifically - TradeOffer's constructor assumes Unciv.Current.gameInfo... That'll eb a hassle to deal with...

MultiplayerScreen cleanup

EventHub removal - Removed 'MultiplayerGameDeleted' event

EventHub removal - Removed 'MultiplayerGameAdded' event

EventHub removal - 'add multiplayer game' no longer works through EventHub

Disallow creating "multiplayer" games with only AI and spectator

EventBus removal - deleted GameSounds, play mp sounds directly

There is no SettingsEvent, no one's listening for settings changes

EventBus removal - remove 'settings updated' sound playing via eventbus

By SomeTroglodyte:
- Commenting UnitManager.unitList stuff 
- Fix Invest quest stays forever 
- Minor Scenarios UX improvements 
- Console autocompletion can display *all* possibilities