5 New Levels!

Hi there!

I've added 5 new levels interspersed between the old set of levels. This should give the game some more content and also smooth the learning curve a little.  I haven't done the most thorough testing of these new levels, so let me know if I missed an easy way to break any of them. There are now 20 levels in total, with the new final level being especially difficult (hopefully). Good luck!