0.7 - more major updates!

After some great feedback from PeoplesChamp, I added:

• Enemy sound variations
• Adjusted some sound volumes
• Tweaked the shield price to make it more worth the price
• Randomised the enemy attacks
• Changed the player hurt sound
• Added camera shake for explosions
• Tweaked difficulty scaling slightly

I'd love to hear any feedback you all have and thank you for playing!