fixes directories in Doxyfile

Doxyfile.in

@@ -790,8 +790,8 @@ WARN_LOGFILE           =
 # spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = @CMAKE_CURRENT_SOURCE_DIR@/
-                         @CMAKE_CURRENT_SOURCE_DIR@/filval/
+INPUT                  = @CMAKE_CURRENT_SOURCE_DIR@/ \
+                         @CMAKE_CURRENT_SOURCE_DIR@/filval/ \
                          @CMAKE_CURRENT_SOURCE_DIR@/filval_root
 
 # This tag can be used to specify the character encoding of the source files