RFR 8139829: JShell API: No use of fields to return information from public types

[Robert Field]

Please review....

Bug:
     https://bugs.openjdk.java.net/browse/JDK-8139829

Webrev:
      http://cr.openjdk.java.net/~rfield/8139829v1.webrev/

Webrev before (per Joe's suggestion) I changed all <code>abc</code> to 
{@code abc}which introduces a lot of noise in the webrev:
      http://cr.openjdk.java.net/~rfield/8139829v0.webrev/

The generate API docs:
      http://cr.openjdk.java.net/~rfield/jshell/

Thanks,
Robert