Twin Stick Shooter Updates

I added hearts as the health UI in the game, later I will make it so when the player gets hit by the enemy it will take away the hearts. I modeled the hearts in Blender and rendered them out as a PNG image so that it can be imported into Unity. The enemies can now spawn and follow where the player is going and they they can also be destroyed when heir health reaches to 0. I also imported the grass field model from Blender into Unity and duplicated them multiple times to make a tile pattern for the ground.