config-panel in drscheme:language:language<%>
This method used by the language configuration dialog to construct the "details" panel for this language. It accepts a parent panel and returns a get/set function that either updates the GUI to the argument or returns the settings for the current GUI.
( -> (case-> (-> settings) (settings -> void))
send a-drscheme:language:language config-panel parent)
parent : (instanceof panel%)