[doxy] Doxygui: restore coverage of full GUI, add Img3D ()

Merging branch 'doxy'  into 'main'.

See merge request !1134

Doc/Doxygen/gui/Doxyfile.in

@@ -897,7 +897,8 @@ WARN_LOGFILE           =
 # spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = @CMAKE_SOURCE_DIR@/GUI/View
+INPUT                  = @CMAKE_SOURCE_DIR@/GUI \
+                         @CMAKE_SOURCE_DIR@/Img3D
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses