Added enemy class, which has methods for its movement algorithm, and an entity scanning method, which iterates through the towerLayout array and checks if the range of that tower will damage the enemy, and subtracts that damage from it. The method also checks if there are towers within range of the enemy, (3x3 square centred about the enemy) and does damage to those towers as well.

If the enemy makes it to the end of the board, it will do damage to the player until it dies or the player dies, ending the game.