0.5 - Playing with formatting.

Apparently I'm hammering on this thing a fair bit.  

The transition from 0.4 to 0.5 contains only one major rules change (it adds a simplified "XP and levels" setup).  

The rest of the changes are all format and art in the front half of the text (though there's quite a lot of that), starting to grow a 'look' for the game.