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.
POM Changes
Spigot Timings

Adds performance tracking timings all around the Minecraft Server, and improves the usability of the /timings command

Plugins can track their own timings with CustomTimingsHandler
Add PlayerItemDamageEvent
BungeeCord Support
Add Arrow API
Add Particle API
Define EntitySpawnEvent and SpawnerSpawnEvent

Defines EntitySpawnEvent and SpawnerSpawnEvent. Adds BUKKIT-267 and BUKKIT-1559
Entity Mount and Dismount Events
Update Depends

- All of these changes have been reviewed to be binary compatible and in general contract compatible with previous versions of the libraries.
InventoryClickEvent getClickedInventory

Add InventoryClickEvent.getClickedInventory. Adds BUKKIT-4495
Plugins currently have to do the logic themselves on the raw slot ID
in order to determine the inventory clicked. This provides the logic for plugins to
readily identify which inventory was clicked.
Added getAllSessionData() to the Conversation API.
Catch Conversation API Errors
Player Collision API
Expand Boolean Prompt Values
Add Getter for Entity Invulnerability
Add respawn API.
Fix Plugin Message API Disconnects
Fix Tab Completion for Some Commands