Update 0.2.2

This update contains the following:

• (Campaign) Unarmored flying saucers stop spawning on level 9 or above
• (Endless) Enemy health now scales with waves (up to 40%)
• (Endless) Enemy damage now scales with waves (up to 50%)
• Added loading screen tips
• Clicking Restart in level completed menu no longer affects your Campaign progress
• Improved the appearance of unarmored flying saucers