Added coverage generation to "pom.xml" of following projects: VadereGui, VadereSimulator and VadereState

Now, coverage report is generated (under "<project>/target/site/coverage-reports/") when using

  mvn test

Extended "pom.xml" to generate coverage reports in CSV, HTML and XML by using "jacoco-maven-plugin".

Generate reports by executing:

  mvn test

Generated reports are located in:

  <project_root>/target/site/coverage-reports

Now, this Maven config can be used to activate report generation in Gitlab.

Dev/bugfix

Following Issue's have been fixed with this patch:
- issue #34 JComboCheckBox NullPointerException on dropdown (OS: Windows)
- issue #30 Predefined Attributes for outputprocessors
- issue #26 Quicksave feature ist komisch
- issue #23 Undo/Redo Funktionalität unzuverlässig
- issue #16 Topography creator: esc sollte einen Zeichenvorgang abbrechen
- issue #9 Postvis: Photo und Video Export

See merge request !21

were part of the stack. This exceptions are caught in the actionPerformed method
and logged to the console on Log Level "Debug" with a simple "beep" sound for the user
to notify an empty stack

for switching back after hitting the esc key.
The Action might be initialized on two different spots. Thus in the PostvisualizationWindow
and the TopographyWindow the initialization is defined.

The Preferences.userNodeForPackage map returned the path specified with a dot at the end of the path.
Which resulted in a malformed path string without any critical effect.

To boost the usability of the Image and Video export a filechooser has been included, where the default name of the exported data fits the previously optionless default name

update migration assistent such that one can choose from based on which version a project should be reimigrated.