Please review clarification of java.time serialized form

[roger riggs]

The specification of the serialized-form[1] of the java.time classes has 
been
improved in response to issue 8024164: JSR310 serialization should be 
described in detail

  - Add descriptions in the Ser classes of the mapping between the type 
bytes and
    corresponding serialized classes.
  - Add missing specification of the serial data to writeReplace methods
  - Add missing readResolve methods that prevent deserialization from 
improperly formatted streams.
  - The Era that are Enum's do not need customized serialization;
    remove unused writeReplace, writeExternal, and readExternal methods,
    remove unused java.time.chrono.Ser type codes for *Eras and renumber.

[1]: 
http://cr.openjdk.java.net/~rriggs/javadoc-serial-8024164/serialized-form.html

Webrev: http://cr.openjdk.java.net/~rriggs/webrev-serial-8024164/
Javadoc: http://cr.openjdk.java.net/~rriggs/javadoc-serial-8024164/

Please review and comment.
Thanks, Roger