[cob_obstacle_distance] Investigate synergies with MoveIt-oriented approaches

[fmessmer]

Maybe cob_obstacle distance might be replaced by using a more MoveIt-oriented approach as in cob_collision_monitor package....investigate synergies between cob_obstacle_distance and ipa320/cob_manipulation#54
Also, have a look at https://github.com/koellsch/obstacle_distance

[fmessmer]

cob_collision_monitor is rebased in ipa320/cob_manipulation#61 - and merged

[fmessmer]

Topic and Service Interfaces (types) should be kept as they are now...in order to interface with the current implementation of cob_twist_controller.

Once the modified collision_monitor is used, maybe maintaining a map with keys being the "links_of_interest" and the value being the "distance to the closest obstacle/robot_link" would make several instances of cob_obstacle_distance (per component) obsolete...thus reducing load!

[fmessmer]

Development has been started in https://github.com/ipa-fxm/obstacle_distance/tree/feature_registration_service_and_continuous_publisher

[fmessmer]

MoveIt!-based approach is proposed in ipa320/cob_manipulation#64

ToDo:

• separate message/service definitions into "neutral" location (e.g. cob_common)
• use "neutral" message/service definitions within cob_obstacle_distance, cob_obstacle_distance_moveit and cob_twist_controller
• use cob_obstacle_distance_moveit together with cob_obstacle_distance (NEEDS TESTING)
• deprecation of cob_obstacle_distance
• use cob_obstacle_distance_moveit together with cob_collision_monitor

[fmessmer]

all further issues/development is tracked in #101