Small update

Just a small update to fix a few annoying things and add a bit of polish so i can sleep peacefully.

- Rewrote the difficulty progression and enemy spawnrate code so hopefully the spawnrate wont suddenly spike out of nowhere, also the difficulty should now ramp up faster in the beginning and slower later on.

- Added some more flare when you get hit.

- Added little score popups when you kill an enemy.

- Added a second of invincibility after getting hit as well as a nifty timer in the middle of the screen so you know how long you have to live before being able to get hit again.

- Player movement speed very slightly increased.

- The big laser ship should now NOT instakill you.

- The bomb enemy will now follow you much less directly.

- The spawn spots blocking radius slightly increased and now they spawn the enemy slightly faster after being blocked.