Adding autorender() in abstract.php, with a small doc block

TODO

@@ -1,7 +1,7 @@
 # TODO #
 
 - explain before_render() in README
-- adding autorender() in abstract.php
+- explain autorender() in README
 - testing and documenting autorendering features
 - adding an option('display_errors'); by default ini_set('display_errors', 0) in production env, but enabled if env is dev (unless matching option is enabled)
 - explain autoload_controller() in README

lib/limonade/abstract.php

@@ -146,3 +146,19 @@ function before_render($content_or_func, $layout, $locals, $view_path)
   # transform $content_or_func, $layout, $locals or $view_path…
   return array($content_or_func, $layout, $locals, $view_path);
 }
+
+
+/**
+ * Called only if option('autorender') is enabled and rendering $output is_null,
+ * like in a controller with no return statement.
+ *
+ * @abstract this function might be defined by user
+ * @param array() $route array (like returned by {@link route_build()},
+ *   with keys "method", "pattern", "names", "function", "options")
+ * @return string
+ */
+function autorender($route)
+{
+  # process output depending on $route
+  return $output;
+}