Updated the TODO list.
Do not throw EOFException on end-of-line in AbstractParser.
Repair CircularReferenceTestClass so it succeeds and does not overflow.

Cannot use the class itself as the map key and also verify map equality
in the equals() method, since that will cause an overflow.

The tests were failing before that, however, due to the reference equality
check of pre- and post-serialization test objects.
Tidy up CommandParserTest. Removed a duplicate check and some imports.