8167461: jshell tool: Scanner#next() hangs tool
Summary: PipeInputStream.read(byte[]...) should only read available bytes; properly resending exceptions for snippet's System.in and properly closing it; more reliable way to cancel user input while waiting in System.in.
Reviewed-by: rfield

8131023: JShell: System.in does not work
Summary: Pass user input to snippets/remote agent
Reviewed-by: rfield

8134254: JShell API/tool: REPL for Java into JDK9
Summary: Adding the implementation of the jshell (read-eval-print-loop) tool.
Reviewed-by: briangoetz, mcimadamore, psandoz, forax
Contributed-by: robert.field@oracle.com, bitterfoxc@gmail.com, jan.lahoda@oracle.com