Another patch with some balancing, bugfixes and a bit of new content, as I'm working my way to release!

Changes:
- Increased assignments end difficulty, so traveling deeper into eXoSpace will be more dangerous. Increased drops and rewards to balance things out.
- Out of fuel Reaver attack is a bit more dangerous.
- Asteroids are now placed using Perlin noise to make the distribution a bit more interesting.
- Player attacks event in encounters now also triggered for damaging ship for a % of total health.
- Improved encounter random seed handling (i.e. should be more random).
- Traders now almost always sell fuel, and more of it. It is more expensive though.
- Traders do not attack when relations are bad, but they are more expensive.
- Added a number of new encounters.
- Lots of smaller changes to existing encounters.

Bugfixes:
- Random encounter rewards did not give module blueprints.
- Some encounters did not change player attack status correctly.
- Starbase cores no longer offered as reward.
- "Cannot buy module" overrode all other hover messages at trader UI.