Initial commit of KUKA KR120 support package

Added support for the KUKA KR120 R2500 PRO manipulator
Meshes are based on the Unigraphics files found at http://www.kuka-robotics.com/res/sps/8ba89f50-3ccd-4361-9b9a-60bdd0662ac6_KR120_R2500_pro.prt.zip
Note that the rotation directions of the KUKA manipulators are different than e.g. the ABB manipulator. For joint 1 this is implemented using <axis xyz="0 0 -1"/>.
Yes, that would be ideal (imho). The rotations aren't necessary if you change the translation axis. As all frames are at 90 degree angles of each other, that is easily done (just use z instead of x).

Using data coming from the controller has my preference, as it removes one source of errors.