Added class "WaitInAreaEvent" and use it in "Simulation" instead of "WaitEvent" to test scenario files.

Notes:
- Currently, event handling is performed by "OptimalStepsModel".
- In the long run this should be done by agents themselves.
- Then, the model classes can remain unchanged.

VadereState/src/org/vadere/state/events/Event.java:
- Implemented "toString()" method.

Also added unit test "EventTest".

In interface "Model", added default method "update(final List<Event> events)" to process events instead of time steps.

Also, use this method directly in method "updateCallbacks()" of class "Simulation".

No errors occurred in first (manual) tests. In further steps, use "Event" classes everywhere where a simple "simTimeInSec" is used.

# Conflicts:
#	VadereSimulator/src/org/vadere/simulator/projects/ScenarioRun.java

implementation of Bitonic sort on the GPU.

See merge request !30

In "PostvisualizationWindow.java", added button to generate TikZ image.

increase the nTrail for the seating test since it is a test that involves probability therefore a larger sample is necessary.

synchronize scenarioStore access. Use exact exponential function for pedestrian and obstacle potential calculation