[C] Fix setting entity's target. Fixes BUKKIT-1358.

The Issue:

As of the current point, most of an entity's goals override the setTarget method.

Justification for this PR:

With this, doing setTarget() on an entity will actually make them move. For example, making a wolf attack a player (broken in 1.2). 

PR Breakdown:

All this does, is set the goal to the target of the said entity.

Testing Results and Materials:

I tested this by simply spawning a wolf, and setting the target to the player who ran the command. Test found here:
http://www.mediafire.com/download/bd67rjgvj1wpt1f/Test.jar

JIRA Ticket:

BUKKIT-1358 - https://bukkit.atlassian.net/browse/BUKKIT-1358