[New Version] Bonuses - Missiles, asteroid freezing, and new sound effects

• Player destroys a green UFO
• 40% chance to spawn a "missile pack"
• Player rushes over to the missile pack and touches it
• Player can fire missiles for approximately 10 seconds

It's the same process for the "asteroid freeze" can, except the moment the player touches the asteroid freeze can all asteroids on the screen become frozen. Note: during this time if you shoot a large asteroid it will break up into smaller asteroids that move. The same holds true for small asteroids past level 4, if they're shot while frozen they will spawn moving smaller asteroids. Essentially the "asteroid freeze" weapon only freezes asteroids currently on the screen. This effect also lasts for approximately 10 seconds.

I've also added a couple of audio indicators so players know they've successfully grabbed the weapon. Both the missile pack and the "freeze can" disappear after only a few seconds, so you have to grab them quick. Also if either rolls off the screen they're gone, there's no screen wrap for weapon bonuses.

In testing I found both the missile pack and the screen freeze quite useful. Please let me know in the comments below how you like the new weapons.