Works in 1.5.2, 1.6.1 and 1.6.2.
Improved message formatting a lot.
Fixed a bug where tab-completing for a sub command would always show "INVALID_SUB_COMMAND".
Renamed commands back to pd and gu, so that help pages work correctly.
Source only changes:
Changed to Maven build system.
Changed the API.
Will produce a NullPointerException if a new player joins the game and their username is the same as their displayname.
Command: /pd i on an offline player will produce a NullPointerException if using a permission handler that doesn't store offline player's permissions (such as GroupManager).