Allow pointing a frame on the head (ros ticket #4347)

[ahendrix]

The PointHeadGoal contains fields for specifying a frame to point (pointing_axis, pointing_frame), but they are currently unused by the head pointing action. Modify the head pointer in pr2_head_action to use these fields in computing the desired joint configuration sent to the head trajectory controller.

trac data:

• Owner: mwise
• Reporter: sglaser
• Reported at: Tue May 18 20:20:43 2010
• URL: https://code.ros.org/trac/wg-ros-pkg/ticket/4347