ObjectInputStream: handle TC_REFERENCE

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
fixup! WIP: Implement Java-compatible deserialization
ObjectInputStream: handle fields of type String

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
fixup! WIP: Implement Java-compatible deserialization
Handle SC_WRITE_METHOD in ObjectInputStream

Serializable classes can customize how they are (de)serialized by
implementing the writeObject() / readObject() methods. OpenJDK's TreeMap
is such a class, and it is used in its serialized form by Sezpoz (which
is used in turn by SCIFIO).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
fixup! ObjectInputStream: handle fields of type String