RFR 8151755: JShell: Generalization of output configuration

[Robert Field]

To cover the full prototypes of default configuration and any futures, 
the output configuration mechanism is moved to a more general and 
conceptually simpler design (despite a more sophisticated/complex 
implementation).
All formatting is now done by defining fields conditionally on selectors 
which are universal and not order dependent.
The /set format and /set field commands have been merged.
The new '/help /set *' docs and the feedback set-up are now in a 
resource file as the first step towards internationalization.
The /drop command and the message which is generated with an attempt to 
execute corralled code is now integrated into the output configuration 
mechanism..
The format of resolution issue messages can now be properly structured 
depending on the number of unresolved/errors.
In the process of developing tests for the new functionality, the 
ability to overflow the maximum size of history (stored in Preferences) 
was discovered and fixed.

Bugs:
     8151755 jshell tool: properly cover resolution issues in output 
configuration
     https://bugs.openjdk.java.net/browse/JDK-8151755

     8152246 jshell tool: history overflow
     https://bugs.openjdk.java.net/browse/JDK-8152246

Webrev:
     http://cr.openjdk.java.net/~rfield/8151755.webrev/

Sample configuration files -- I have updated proto.modes to the new 
format, and normal mode can be seen (resource file formatted) in 
l10n.properties:
     http://cr.openjdk.java.net/~rfield/formats/proto2.modes
http://cr.openjdk.java.net/~rfield/8151755.webrev/raw_files/new/src/jdk.jshell/share/classes/jdk/internal/jshell/tool/resources/l10n.properties

Thanks,
Robert