Add source encoding to the maven compiler plugin.

This change adds the source encoding to the maven compiler plugin, which
will strictly enforce build consistency on multiple platforms and address
possible compilation issues on some of the source files. The source
encoding unintuitively is system-specified by default.
Deprecate magic values
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
Add missing villager sounds. Addresses BUKKIT-4756
Updated version to 1.6.2-R1.0 in pom.xml for RB.
Updated version to 1.6.2-R1.1-SNAPSHOT for development towards next release.
Correct some magic values. This amends 1f83111208ab3612f384a2e6b65cc28423dc625e