clearer messages when switching to another directory

ldoc.lua

@@ -223,6 +223,7 @@ if args.file == '.' then
    if err then quit("no "..quote(args.config).." found") end
    local config_path = path.dirname(args.config)
    if config_path ~= '' then
+      print('changing to directory',config_path)
       lfs.chdir(config_path)
    end
    config_is_read = true

ldoc/html.lua

@@ -154,7 +154,7 @@ function html.generate_output(ldoc, args, project)
          end
       end
    end
-   if not args.quiet then print('output written to '..args.dir) end
+   if not args.quiet then print('output written to '..tools.abspath(args.dir)) end
 end
 
 return html