[lwa] arm_7_link has wrong orientation

[fmessmer]

Z-axis of arm_7_link should point "away" from the arm!
For schunk_lwa it is pointing "into" the arm.
(This results in problems with cob_pick_place_action where approach and retreat direction is defined wrt arm_7_link coordinate system!)

[floweisshardt]

this depends on the rotation axis of the Schunk modules. what we can do is to add an "arm_tcp_link" which is always oriented "away" from the arm. @ipa-fxm: would that be OK?

[destogl]

This is good idea. This is something I always do (define "arm_tool_link") should I create PR? I currently play with the arm :)

[fmessmer]

@destogl
Sure, contributions are always welcome....Thanks