RFR 8166649: jshell tool: missing --add-modules and --module-path

[Robert Field]

Please review....

Bugs:

     8166649: jshell tool: missing --add-modules and --module-path
     https://bugs.openjdk.java.net/browse/JDK-8166649

     8167462: jshell tool: /help /reload is wrong about re-executing 
commands
     https://bugs.openjdk.java.net/browse/JDK-8167462

Webrev:

     http://cr.openjdk.java.net/~rfield/8166649v0.webrev/

New command-line options:

     --module-path <path>  Specify where to find application modules
     --add-modules <module>(,<module>)*
                           Specify modules to resolve, or all modules on the
                            module path if <module> is ALL-MODULE-PATHs

Thanks,
Robert