clarified init (again): isabelle.Main is responsible to provide basic JVM setup, jedit.jar picks this up (e.g. list of known fonts), plugin cannot be loaded in isolation without isabelle.Main;

--- a/src/Pure/Tools/main.scala	Thu Oct 01 23:26:31 2015 +0200
+++ b/src/Pure/Tools/main.scala	Fri Oct 02 16:56:46 2015 +0200
@@ -20,6 +20,7 @@
     {
       try {
         Isabelle_System.init()
+        GUI.install_fonts()
 
 
         /* settings directory */

--- a/src/Tools/jEdit/src/plugin.scala	Thu Oct 01 23:26:31 2015 +0200
+++ b/src/Tools/jEdit/src/plugin.scala	Fri Oct 02 16:56:46 2015 +0200
@@ -384,9 +384,6 @@
       Debug.DISABLE_SEARCH_DIALOG_POOL = true
 
       PIDE.plugin = this
-      Isabelle_System.init()
-      GUI.install_fonts()
-
       PIDE.options.update(Options.init())
       PIDE.completion_history.load()
       PIDE.spell_checker.update(PIDE.options.value)