added EnemyArcher

archers can now move
archers can now fire arrows
archers will try to remain between 1 unit and 3 units from the player
player draw speed is doubled to 0.5 secs to max draw strength
arrows now have a targets paramiter for valit targets to damage on
colide
turrets now cool down when no enemys are in range aswell
optomization for turrets
added an archer into wave 1 for testing purposes

notes - archers will need path finding for getting closer to and futher
from the player