Matrix Defense v0.2 Update

Matrix Defense v0.2 Update Now Available

# What's new in release v0.2

# Bugfixes
- laser sound not stopped when level ends
- bullets not updated when tower is destroyed
- tower explosion sound not playing
- fixed several flaws in the wave and spawn mechanics

# Improvments
- improved loading time (hopefully not eaten up by the new content)
- added menu item on game over screen to restart the game without quitting
- added sell button (select tower and click sell)
- added wave timer animation
- small timing adjustments