Make /spreadplayers command work. Fixes BUKKIT-4720
Add new sounds to the Sound Enum. Addresses BUKKIT-4756
Update /say to vanilla behaviour. Fixes BUKKIT-4224

Prior to this commit all /say command output would be a generic "[Server]"
prefixed line. This commit changes that by adding the source into the
message, such as a player. By doing this Bukkit more closely matches
vanilla behaviour and gives a more descriptive message to the client.
Add support for command tab completion in the console. Adds BUKKIT-4168

This commit corrects tab-completion logic to consider non-player command
senders.
Pulling all pending Bukkit-JavaDoc changes
Add SpawnReason for Entity Reinforcements. Fixes BUKKIT-4744