New track, fixed typos and balance

Thanks to everyone for feadback - now with your help I can improve this piece of game maker's art a little bit.

Here is what changed:

• First, and most important - I added awesome ending track from Nafatenmar.  You still have to defeat boss to hear it, but, thank God, now it is easier.
• Last level balance fixed - now it has more reasonable difficulty.
• Extra mediators are not disappear now, if you try to take more than 3 of them.
• Some embarrassing typos fixed also.