added powerup class

Signed-off-by: sabot <sabot@inuits.eu>
added rudimentray powerup dropping from dead hexagons

Signed-off-by: sabot <sabot@inuits.eu>
added (dumb) enemy paddle

Signed-off-by: sabot <sabot@inuits.eu>
added skeleton for enemy ai manager

Signed-off-by: sabot <sabot@inuits.eu>