Move attached structure options into render element

@@ -47,7 +47,7 @@ function chessboard_init() {
   // Process structures.
   foreach ($cache as $item) {
     if (isset($item->data['#attached'])) {
-      chessboard_process_attached($item->data);
+      _chessboard_process_attached($item->data);
     }
   }
 }

When updating from earlier versions this code will be dealing with old data, effectively setting preprocess to TRUE, instead of the desired FALSE. As a result a new set of aggregrates may be created.
If we think this is bad, we need an update function.

I'm not to keen on throwing database update routines for patch level updates.
This old data will live for 25 hours. Only sites that aggregrate css and update from a previous version of Chessboard Renderer will see the number of aggregates grow. Administrators may stop this by flushing their filter cache after updating.
Reported installs: 7 sites currently report using this module.
After some debating I decided to commit this and prepare for a new release.