HyperFighter version 0.0.3

Here's what's new in this version

• enemy bullet hitboxes are now smaller to avoid hits without visible physical contact
• bullet behaviour is now bound to the bullet type, not enemy type (so bullets of one colour will always act the same way)
• enemies now spawn in waves, as such all enemies of a wave need to be destroyed before progressing to the next one
• added a new enemy that stays on the right side and targets you as long as you don't destroy it
• new smaller explosion for when you're hit by an enemy bullet
• the demo level is now a bit longer (max score 12100)