Unnamed Medium Update

Not giving up on this game yet! Also a new cover image, which I think is way better than the old one.  Anyway, onto the changes.

• Added a much needed tutorial
• Add new mode "Challenges", which unlocks new content upon completion. Challenges in red are incomplete. Currently there's only 2 challenges.
• Added 1 new Abnormality
• Added 2 new unlockable Abnormalities
• Nerfed the effects of Forsaken Murderer
• Blubbering Toad's effect will now activate even if there are bullets on screen.
• Blubbering Toad will now replace its own tongue if there is one already on screen.