Merge remote-tracking branch 'origin/master'

# Conflicts:
#	app/src/main/java/de/hems/trafficsim/MainActivity.java
#	app/src/main/java/de/hems/trafficsim/Track.java
#	app/src/main/java/de/hems/trafficsim/Vehicle.java
#	app/src/main/java/de/hems/trafficsim/Worker.java