tree ik solver clashes with older version in the kdl library

[bit-pirate]

Our custom tree IK solver has been added to the KDL library some months ago and made it into the ROS distribution recently (at least in Groovy).
So now the one in the tree_kinematics package is clashing with the one in the KDL library.
We need to check the differences between both and then either remove the version in the tree_kinematics package or rename it, if it contains fixes and improvements. In the later case we should send a patch out.