Boss balancing v0.938.0

We went through all the bosses and made sure they are better adjusted. Some of them had huge amounts of damage once they are very high level. They were manageable, but you'd have to have a team with powerful tanks, and they were too hard for more offensive and fragile teams. Now, some of them have a trade-off with more health and lesser damage. Also, the movement speed of all bosses went through the roof once they got to a very high level. So now, they all have fixed movement speeds that are appropriate for each of them. And other adjustments and fixes regarding boss units. Overall they are not that much easier, but their stats are better balanced so different types of gladiator teams have a chance.