Boss Cannon Needs More Warning

[randomPoison]

One of the biggest ways for me to die when playing is for the boss to hit me with its main cannon. But with the increased amount of stuff going on it's now much harder to see the cannon going off. Since the cannon does so much damage (half the player's health currently) it winds up really punishing the player for not being able to follow everything that's going on in the game.

To fix this, I think we should have the canon have a laser sight to show where it's aiming, and give some more indication when it's firing (a charge-up noise, have the laser sight flash, etc.).