0.49.0 - For Ringalowda!

This release further expands AI of the ships in the game. I refined the mineral-catching behaviour, added excavation logic and fine-tuned all the parameters. Specific changes:

• AI ships can now dig up the minerals themselves.
• Ships will now value their life more, abandoning output in grave danger.
• Fixed amount of propellant in AI controlled ships, so they don't run dry so quickly.
• Ships will now return to the station when they are low on propellant.
• AI will no longer use all the power just for defense, leaving them drifting helplessly.