Make it so the game now has 6 levels

[CameronJung]

This includes the current level which fulfills the niche of a medium battle, thus 5 more levels are needed

Requires:

• [x] #13
• [x] #15
• [x] #18
• [x] #17
• [x] #19
• [x] #16
• [x] Set up the next level buttons for the appropriate order