Multiple Balance Changes - Please Read:

1) Incereased chance of spwaning Kamikaze enemies - 1/3 up from 1/5
2) Decreased chance of spawning Large enemies - 1/6 down from 1/5
3) Decreased chance of spawning Normal enemies - 1/2 down from 3/5

4) Enemies now scale in difficulty with the number of bosses defeated.
   In general, minibosses are 1.5x as hard if they the second boss and 2x as
   hard if they are the last miniboss.
5) Blink miniboss base stats slightly buffed (He was easier than Large enemies
   before)
6) Fast Miniboss base stats slightly nerfed, but lategame improved (He was
   impossible to defeat or escape before in early game)
7) All enemies gain health with level except 1 hp turrets.
8) All mobile enemies gain movespeed with level
9) Most shooting enemies gain cooldown reduction with level

10) Final boss slightly buffed. Turrets moderately buffed in final boss fight.
    The fight should now be quite difficult, but doable with lots of skill and
    maybe a little luck.

Re-implemented miniboss spawning mechanics. Minibosses should now spawn at most
onc of each type in an instance without any re-rolling of random numbers.