Java "Space Game" Demo from https://www.youtube.com/watch?v=hXImR8Wm53M series from RealTutsGML with some enhancements

Includes some code enhancements from the nice video series from RealTutsGML (really cool stuff, thanks!). As an example:

• Split functionality in diffent packages
• Using Generics for controllers and created two separate controllers (one for Enemies another for Bullets)
• Used better names for Interfaces (EntityEnemy and EntityFriendly instead of EntityA and EntityB)
• Physics collition methods do the loop and return the object (or null) instead of true or false
• Enhanced Animation class to accept any number of images using ArrayList structure.
• Endless scrolling background
• Added colors for health bar depending on how close to deadth we are
• Added lives counter (starting by 4) that reduces after

More to come thanks to my 7-year's-old daughter's feedback who loves this game ... :)