Improved error handling in tutorials input files.

src/tutorials/java/fr/cs/examples/KeyValueFileParser.java

src/tutorials/java/fr/cs/examples/bodies/Phasing.java

...ials/java/fr/cs/examples/propagation/DSSTPropagation.java

...orials/java/fr/cs/examples/propagation/TrackCorridor.java

...als/java/fr/cs/examples/propagation/VisibilityCircle.java