Some shield and event-related fixes

- Make the FLAN-495 and KOOL-AYD prettier and more friendly to the ears.
- You'll no longer instant-100% on a re-visit to a Megaboss event level.
- You can no longer advance past a Megaboss event level until you defeat the
  boss. You can still visit the Outpost, though.
- Minimum Shield Capacity is 10.
- Made the TOJI-K0 lightning cast farther and no longer love the ceiling/ground
  so much.