using LOGNAME variable rather than strings for logging

[mlautman]

Description

Using name_ variable for logging rather than "robot_state"

Checklist

• Required by CI: Code is auto formatted using clang-format
• Extended the tutorials / documentation, if necessary reference
• Include a screenshot if changing a GUI
• Created tests, which fail without this PR reference
• Decide if this should be cherry-picked to other current ROS branches
• While waiting for someone to review your request, please consider reviewing another open pull request to support the maintainers

[rhaschke]

In other files, we have used a static variable LOGNAME, which I would prefer here as well.
I think, we shouldn't clutter the class's API with another member variable.
If you insist in using a member variable, I would prefer to name it LOGNAME as well. What do you think?

[mlautman]

@rhaschke I'm not sure that declaring the variable outside the class would work. In this case name_ is used in both robot_state.h and .cpp so we would have to declare the string in the .h. This results in redefinition errors if we have multiple classes that share namespace as is the case with moveit_core. Philosophically, I don't see the rational for keeping this data outside of the class in a shared namespace as this variable is being used by the class to relay to the logger it's identity. While planning_scene_monitor uses LOGNAME, it is the only one that does so. Since trajectory_execution_manager uses name_, I see these as equally valid. name_ seems better to me because it implies the name of the class whereas logname_ implies the name of the logger. (Also, since it is a member variable, it would need to be lower case)

[rhaschke]

The single use case in .h I would move into .cpp indeed. There is no reason for this function to be inline.
But my key point is that the name_ member suggests that a RobotState instance can be named. The LOGNAME variable will much better emphasize the usage of this variable.

[davetcoleman]

I agree with @rhaschke's point that the name_ of a RobotState would lead me to expect "panda" or "pr2" for example.

I also agree that there shouldn't be function code in the .h file and that should be moved. inline is not necessary with modern compilers.

Perhaps CLASSNAME would be best, but I don't like the two extra characters so agree with LOGNAME

Please document this new "standard" on the Contributing page:
http://moveit.ros.org/documentation/contributing/code/

[mlautman]

@rhaschke Requested changes made. I also made the same formatting change to robot_model.cpp and robot_state/conversions.cpp.