Prerequisites for merging PR 129 in soma_utils

[JannisW]

This PR is a prerequisite for merging https://github.com/SoMa-Project/soma_utils/pull/129

It does the following things:

• Adding the chosen node (the one in the graph that was chosen by the planner as the final node) as a return value of the planner service.
• Unifying the name of the PreGrasp control mode along different HAs (the name is now PreGrasp. Before it was either PreGrasp (WallGrasp) or Pregrasp (SurfaceGrasp))
• Removing some semicolons from the code... someone really prefers C-style syntax ;)