Milestone 6.9.0 Released! (Experimental) — Xenonauts 2 Steam update #391647

This update is also only accessible by switching to our Experimental branches (instructions on how to do so here) - although please be aware they have slower load times and worse performance than normal builds due to the extra logging they contain!Unfortunately this update breaks save game compatibility - the bug where the Battleships were not spawning in Phase 5 can't be fixed in existing campaigns. I'll put 6.8.0 on the Experimental Legacy branch so people can continue playing it, but you'll need to capture the Eternal on the UOO Bridge Assault mission alive if you want to complete the game.Changes:The Air Combat section of the tutorial has now been added to the existing tutorial.Added the final side-on art for the aircraft weapons in the air combat UI.Added an explanatory popup when the first UOO mission is unlocked, explaining you need to click the new button to launch the mission (a...