This reverts commit 35976b6f.

# Conflicts:
#	Scenarios/ModelTests/TestPsychology/CognitionAndBehavior/scenarios/12-CounterFlow-SBEnabled.scenario

Also, moved two long-running scenarios to "Scenarios/Demos" to shorten
the integration test phase of Vadere.

Also, deleted dummy test files for renaming "event/events" to "stimulus/stimuli".

Two aspects are missing so far:
- Writing a migration to rename nodes in JSON representation.
- Rename controller classes and unit tests.