Moved images that are only used by the C++ help code out of core;...

...takes care of something that should have been dealt with a long
time ago.

data/core/help.cfg

@@ -1,16 +1,5 @@
 #textdomain wesnoth-help
 [help]
-    # FIXME: This is a kluge to keep the reference checker happy
-    # These are actually used in the C++ portion of the help engine.
-    # The fact that they're duplicatively listed here is a maintenance
-    # problem waiting to happen; fix it in 1.7
-#ifdef __UNUSED__
-    image=help/topic.png
-    image=help/open_section.png
-    image=help/closed_section.png
-    image=help/indentation.png
-#endif
-
     [toplevel]
         sections=introduction,gameplay,units,abilities_section,traits_section,weapon_specials,factions_section,terrains,commands,encyclopedia
         topics=about,license