New update: Unbreakable bricks tweaked and crash fixes

A small update to fix some issues with the new maps introduced in the latest of content updates I've been making to Roguebreaker free since release.

• Added: Five variations of the white-bordered unbreakable bricks. The more you hit them with balls, the more they visually degrade, letting you know it's doing something.
  
  
• Fixed: No longer crash on trying to load Flood map
  
• Fixed: "Invader" map no longer has breakable bricks surrounded by breakable bricks
  

Thanks again for trying my game, it would be possible without people (like pasechnikk) giving me feedback in the discussion board here!