Spiritus Astrum [P0-B13]: p1543: Towards Early Access

I have been doing a lot of debugging, and have finished another complete test run of the third campaign.

I have fixed a large number of bugs and made a lot of improvements to the AI system and persistent object spawning, as well as the campaign system.

The space combat system has also received some minor improvements, but I need to spend more time on this later.

There is still quite a lot of debugging, etc, to do though.