[jrubyscripting] Add JRuby REPL and other utilities inside karaf console

[jimtng]

Add Karaf console utilities for JRuby, including a REPL environment that runs inside the same script engine as normal rules.

openhab> jrubyscripting 
Usage: openhab:jrubyscripting info - displays information about JRuby Scripting add-on
Usage: openhab:jrubyscripting shell - starts an interactive JRuby shell
Usage: openhab:jrubyscripting gem - manages JRuby Scripting add-on's RubyGems
Usage: openhab:jrubyscripting update - updates the configured gems
Usage: openhab:jrubyscripting prune [-f|--force] - cleans up older versions in the .gem directory
Usage: openhab:jrubyscripting unload - unloads the console's script engine

openhab> jrubyscripting info                                                                                                   
JRuby 9.4.12.0
JRuby Scripting Library 5.35.1
GEM_HOME: /home/openhab/openhab-jruby/tmp/openhab/conf/automation/ruby/.gem/9.4.12.0
RUBYLIB: /home/openhab/openhab-jruby/tmp/openhab/conf/automation/lib/ruby/personal
Script path: /home/openhab/openhab-jruby/tmp/openhab/conf/automation/ruby

JRuby Scripting Add-on Configuration:
=====================================
rubylib: /home/openhab/openhab-jruby/tmp/openhab/conf/automation/lib/ruby/personal
local_variable: transient
local_context: singlethread
gems: openhab-scripting=~>5.0
gem_home: /home/openhab/openhab-jruby/tmp/openhab/conf/automation/ruby/.gem/{RUBY_ENGINE_VERSION}
dependency_tracking: true
require: openhab/dsl
check_update: true

openhab> jrubyscripting prune                                                                                                  
Some files and directories exist in '/openhab/conf/automation/ruby/.gem' outside of your configured gem home '/openhab/conf/automation/ruby/.gem/9.4.12.0'.
They may have been left over from previous installations or updates.

  /openhab/conf/automation/ruby/.gem/9.4.9.0/
  /openhab/conf/automation/ruby/.gem/test1/
  /openhab/conf/automation/ruby/.gem/test2/
  /openhab/conf/automation/ruby/.gem/test3/

Press Enter to delete them or Ctrl+C to cancel.

Deleting: /openhab/conf/automation/ruby/.gem/test3/4/5/6
Deleting: /openhab/conf/automation/ruby/.gem/test3/4/5
Deleting: /openhab/conf/automation/ruby/.gem/test3/4
Deleting: /openhab/conf/automation/ruby/.gem/test3
Deleting: /openhab/conf/automation/ruby/.gem/test2
Deleting: /openhab/conf/automation/ruby/.gem/test1
Deleting: /openhab/conf/automation/ruby/.gem/9.4.9.0
openhab> jrubyscripting prune                                                                                                  
No files or directories to delete from /openhab/conf/automation/ruby/.gem

The REPL shell supports:

• A rudimentary tab completion on item names, constants, DSL methods, and local variables.
• History recall (up/down arrow) within the same session

This next screenshot shows it running in my production instance:

An alternative implementation can be done should openhab/openhab-core#4635 be merged. For the time being, this PR stands alone and will work without the linked core PR. When the core PR is merged and this is refactored, we can remove the dependency to karaf in pom.xml.

If the core PR gets merged, I can refactor this later if necessary. I don't want the core PR be a blocker for this PR though.

[jimtng]

Updated to use repl code from the helper library openhab/openhab-jruby#405

[ccutrer]

you need to run mvn i18n-generate-default-translations, no?

[ccutrer]

if the whole group is already advanced, does the individual item need other be advanced?

[jimtng]

I tried removing the advanced tag from the individual items, whilst keeping it in the group. This would make them show up even when the "advanced" checkbox isn't selected. It seems like a "bug" somewhere, but for the time being we'll have to stick with how it goes.

[ccutrer]

do we really need console? or would session be enough? (really, all I'm using right now is terminal - which you get from session). then you don't event need the JRubyConsole. in the one or two places that need session, just pass it through from execute().

[jimtng]

I've changed it to just $terminal. However, we still need JRubyConsole because the OSGiConsole class from core is in an internal package. We still want to have a console object to keep a resemblance to the standard ConsoleCommandExtension in case we need to refactor this back if openhab/openhab-core#4635 is accepted.