Update 0.7.3

This update contains the following:

FEATURES

• Added 4 new alien groups
• (Standard Mode) Level 10 waves 2 and 4 have been changed
• Clicking Reset Progress or Clear High Score in main menu now prompts you

GAMEPLAY

• Made some alien groups move and shoot faster

VISUALS

• Added a message that shows when you get a powerup
• Removed "Multishot", "Increased Damage", "Faster Fire Rate", and "Faster Speed" colored text