Patch-Fix #4

- Fixed accumulation of a large number of pirates after failed contracts;
- Fixed the appearance of merchant ships far from the sector, when hyperjumping;
- Fixed disappearance of patrol ships from sectors;
- Fixed a few more bugs with mining (yes, there were really a lot of bugs!);
- Now different ships have a limit on the maximum power of the shield. A light fighter cannot mount a shield against a heavy ship.