Upgrades, Health Bar and more

Added:

-4 upgrades to the bullet damage/speed and movement speed. You can choose an upgrade in the level up menu after every level you earn, in which you can choose one of the two options or skip upgrading.

- A health bar for the player 

- You now can lose the game, by getting damaged 3 times.

- When you start a new game you lose all progress.

- You now attract xp orbs from a further distance.

- At the main menu there is now an exit button, which exits the game

- At the main menu there is now an settings button, no functionality yet added.

-More randomized xp spawns after enemy death