DumpStack: add TODO reminder

Most of the logic in this class will be obsolete upon the next release
of scijava-common.
DefaultLUTService: initialize lazily
ScriptLanguage: clean up style and imports
Use ImageDisplay-specific context menu

For the context menu items intended to be used with ImageDisplays,
let's use a more specific menu root string.

This change is in preparation for
org.scijava.plugin.Plugin#CONTEXT_MENU_ROOT being deprecated in the
next release of scijava-common.

Now, it may be the case that this whole idea of "context menu roots"
doesn't work well once we flesh out various context menus further.
I have my doubts. But we'll give it a try first (iterate faster!)
and see how it goes.
DefaultScriptService: tweak style
DefaultScriptService: make high priority

We want the ScriptService to register its modules with the
ModuleService *before* the MenuService gets fully initialized
and generates a menu structure.
WIP

1) Why does the label attribute not work:
// @OUTPUT String appInfo(label = "App Info")

2) Why is scijava-apps.bsh *still* not in the Plugins menu?