opibuilder: Add preference java_script_engine=RHINO or JDK

Default to the engine in opibuilder/lib/rhino/js.jar, but allow testing
the JDK's Rhino or Nashorn.
See https://github.com/ControlSystemStudio/cs-studio/issues/723
org.csstudio.scan.ui.feature: Update version

.. because of tycho build?!
Merge pull request #729 from ControlSystemStudio/bug723_rhino_vs_jdk

opibuilder: Add preference java_script_engine=RHINO or JDK