Rewrite BukkitMirrorTest
Fix failing BukkitMirrorTest
Add damage modifier API in EntityDamageEvent. Adds BUKKIT-347, BUKKIT-4104

This commit adds API for the enchantment, armor, potion and other
modifications to damage done to an entity. These damage modifiers are each
editable editable via a getter and a setter. This addition allows for more
accurate modification and monitoring of damage done to/by an entity, as it
displays the final damage done as well.
Replace getOnlinePlayers to provide a view. Adds BUKKIT-5668
Update Bukkit for Minecraft 1.7.10
Pulling all pending Bukkit-JavaDoc changes
Recalculate damage modifiers in event for old method. Fixes BUKKIT-5681

When we added the new API in EntityDamageEvent to give control over the
various things that modify the final damage done we caused a change in
behavior for users of the old #setDamage(double) method. Before changing
the damage would happen before the modifiers were calculated so they would
be based on the final damage value from the event. Now they are calculated
at the beginning so changing the damage does not change the modifiers.

To allow the old style and the new to coexist we now expose the vanilla
modifer calculations to the event in the form of Function objects. These
are used in #setDamage(double) to calculate the difference in the modifier
between the old damage and the new and apply this difference to the current
modifier. The difference is between the vanilla values for both damage
values and is applied on top of the event's modifier value as this should
make old and new API usage work together in a way that isn't surprising.