Fix tired artillery bug

Bugfixes

• Fix bug where offensive buildings would sometimes get tired and stop firing
• Fix bug where mortar shells would magically pass through attack boats on fast forward speed

Balancing

• Reduce Eagle builder bay build speed bonus from 15% to 10%
• Reduce Eagle hit points from 2,800 to 1,800
• Reduce artillery build time from 180 to 120 seconds
• Increase air turret hit points from 220 to 310
• Reduce deathstar laser duration from 5 to 4 seconds

Other

• Make explosions look even better