Increase Ender Dragon's acid pool damage along with the melee damage

A new config option will be added for this. My only concern is that the acid pool's damage is magic damage so (other than with Protection ench) there's no real way to protect yourself. I will do some testing.

Perhaps if that is too overpowered, maybe the ender dragon could start firing more of them in a row?

I mean, it will be configurable and I'll do tests to prevent it from begin OP after a few drakes.

Closed via 3eb4447