Callback Based Selectors

[Alan Bateman]

I've re-based the patch that adds select(Consumer<SelectionKey>) and 
friends. This follows the changes for JDK-8201315 so the action is 
invoked while synchronized on the selector and the selected-key set, not 
the key set for registrations.

    http://cr.openjdk.java.net/~alanb/8199433/webrev/

There's a still a bit of work to do on the Solaris event port 
implementation related to error recovery, also additional tests will be 
needed, but otherwise I think all the interactions with the existing 
spec have been worked out.

-Alan