Fix crits breaking multi-hit moves

If one hit crit the rest would negate the atk penalties/def boosts as
well

Also I moved some stuff around to decrease redundancy
Chain stat modifiers in the proper order

10: Figure out a way to apply these directly to the stat later
...
6: Target Ability
5: User Ability
4: Target's Ally Abilities
3: User's Ally Abilities
2: Target's Item
1: User's Item

To be honest it's mostly for posterity's sake as well as to match the
soon-to-be-corrected base power modifiers. At the moment all stat
modifiers are either *1.5 or *2 which have the same result no matter
which order you chain them in. However a mod or ability/item in the
future could add a value that isn't as clean.
Merge remote-tracking branch 'upstream/master' into damage
Chain base power modifiers

onBasePower events now affect the base power modifier as opposed to the
base power directly. Also some moves had their base power changes moved
from basePowerCallback to onBasePower. These moves affect the modifier
and not the base power.

Note: The effects of weather and burn are still incorrectly applied as
base power modifiers
Chain base power modifiers in proper order

8: User Ability
7: Target Ability
6:  User Item
5: Target Item
4: Move Modifers
3: Other User Modifiers (Helping Hand, Charge)
2: Other Target Modifiers
1: Field Modifiers (Water Sport, Mud Sport)
Merge pull request #368 from V4Victini/damage

Many Damage Fixes