Adding services to create and remove nodes and edges

[argenos]

Is your feature request related to a problem? Please describe.
The creation of the topological map is done manually in a script. To enable the robot to create this map automatically, a first step is to enable the creation and deletion of nodes and edges.

Describe the solution you'd like
In addition to creating and removing nodes, there should be services for annotating or adding data to both nodes and edges

Describe alternatives you've considered
A ROS service that adds the above mentioned functionality.