Nestmates spec updates

[Dan Smith]

FYI, as the JVMS changes for nestmates have moved forward toward integration with the official JVMS, there were some substantial updates to improve presentation. For clarity and transparency, I've updated the document that appears in my CR space, along with those attached to JBS issues, to reflect these changes.

http://cr.openjdk.java.net/~dlsmith/nestmates.html

We also concluded that we should not touch JLS 13.1 in the JLS updates. Revised document:

http://cr.openjdk.java.net/~dlsmith/nestmates-jls.html

—Dan