(ScriptEngineHandler) Properly clear engineHandlers when closing
(ScriptingEditor) Make it more explicit how the editor listens to preferences changes
Remove listeners when closing a ScriptingPanel

Also make the ScriptingPanel responsible for their own file saving on close
Remove listeners on the ScirptingConsole
(ScriptEngineHandler) Comment the fact that the engineHandler does not listen to plugin loader events
(ScriptingPanel) Remove reference to tabbedPane, get it through the editor
(ScriptingEditor) Avoid creating an Untitled pane when not needed, and properly clean the corresponding Panel
when removing the default one and the user opens a file
(BindingsScriptFrame) Release the reference on the engine when exiting
(ScriptingPanel) Include the autocompletion uninstall in the cleanup
(ScriptEngineHandler) clear the engines hashmap when clearing the engines (allows more garbage-collection)
(ScriptEditor) Save editor state at each file open/close to help when crashing
Merge pull request #21 from tlecomte/leak-fixes

Leak fixes