Renamed the DotExporter plugin class to its correct value
Forgot to commit the header file for the UtilityBase class
Added skeleton files for experiment context plugin

The experiment context plugin shall hold information about
a) what entities were part of the experiment at hand
b) what was the intended purpose of the experiment
c) additional notes about the current situation

Also, the plugin should be able to export files containing this information (into a designated .xml file for example).
Made the experiment-context plugin properly accept data and export a meta file

The metadata.xml file created by the plugin is now stored in the current experiment's folder. Its data fields are purely determined by what the plan execution entity sends to it.
Publish unique designators only once; correctly tearing down prematurely ended contexts

Designators were published twice due to external calls. This is now fixed by taking the already known unique designators into account when publishing new ones. Also, prematurely ended contexts were not annotated with their success state and their end time correctly. This is fixed now (they get the same flags as the ended context ID that flagged them as prematurely ended).
Probably found the cause for missing designators in the published log topics

When equating a designator that originated from `with-designators` and one made with `create-designator` or `make-designator` (so, not tracked when creating them), they show up in the symbolic log, but not in the database. This should be fixed now.