Levels are now dynamically loaded.

Everytime the player reaches the end of the current level, the next level is loaded, the player's health is restored and the ship is positioned at the start of the new level.

Currently when you reach the end of the last level, the game starts over with the first level. Maybe I will add some "Game Over" screen or high scores page, etc...

The dynamic level loading opens the way to add lots of additional levels. I will need to add some more content to keep them entertaining.