Bugfixing

• Fixed bug where armor health did not dissappear when armor health was 0
• Fixed bug where ninjas set to 'Last' were occasionally ignoring enemies

Balancing

• Adjusted SmokeBomber's upgrades to not deal damage towards armor, and instead significantly increase the value of incremental damage
• Adjusted wave rewards on difficulty
• Player health dependent on difficulty
• Adjusted enemy health to grow steeper
• Balanced various ninja, building, and upgrade costs