Hell Bullet 1.3

I've gathered some feedback and realized that most people won't even beat the first boss because the learning curve is too steep.

So I added some difficulty options to the main menu, with "Hard" being the release difficulty. "Hell" is the new difficulty that should switch the gameplay a bit.

With the new difficulty system, I also added a high score system:

• In the difficulty level "Normal" you get 50% points
• In the difficulty level "Hard" you get 100% points
• In the difficulty level "Hell" you get 300% points