GitLab

- Moved all config classes to package "org.vadere.util.config".
- Renamed:
  * "ExperimentalResources" to "VadereConfig".
  * "ConfigurationSection" to "IConfigSection".
  * "INIConfigurationSection" to "IniConfigSection".
- Revised "config.ini" (renamed keys and deleted unnecessary keys).

improved video and picture making for the PostVis and change the PostVis from time step granularity to simulation time granularity.

* single step mode in GUI:
  Allows the user to step through the simulation one step at a time to
  identify bugs.
* simplify obstacles:
  Merge multiple obstacles based on the convex hull their points create.
  The merge can be undon
* add features to open street map (osm) importer:
  1) import 'open' paths as polygons with a specified width. With this
     it is possible to create walls or subway entrance
  2) add option to include osm ids into each obstacle

In "ProjectView", display a more meaningful error message when an exception occurs during simulation run.

For this, use the text from the inner (causing) exception instead of the outer exception.

New scenario element "AbsorbingArea" is not handled in:
- AbsorbingAreaController (this class is missing completely at the moment).
- MigrationAssistant (must add node '"absorbingAreas" : [ ]' to topography tree).
- DefaultConfig (to be able to change color).
- TikzGenerator (must use "topography.getAbsorbingAreas()" to iterate over the new scenario element).

Extracted filename prefix for snapshots to "messages.properties" and "messages_de_DE.properties" respectively.

Fix #160: In "TikzGenerator.java", use "String.format(Locale.US, ..." to force a dot as decimal separator.

In "TopographyWindow" and "Online/PostVisualizationWindows", replaced "About" button by "Setting" button.

implementation of the gui elements and actions to merge overlapping obstacles. The algorithm sometimes still fail and the undo/redo actions are not jet implemented.