mollom_validate() builds data for non-protected forms

I found this through using Mollom on a site where I had disabled previews on a node type for technical reasons. Doing a preview invokes hook_nodeapi() with the 'view' $op, and I was hooking into that to perform a redirect for the nodes after their creation. I have since updated my hook_nodeapi() to check for a $node->nid, but I also think a fix is in order for Mollom... it builds the node preview content for node forms even if it's not set to protect those forms. So in my case, Mollom was invoking my module's hook_nodeapi() and causing the redirect when I didn't want it to.

Anyways, I've attached a patch that will bail out of mollom_validate()if the form's mode is MOLLOM_MODE_DISABLED. I suppose you could alternately not alter the form at all, but I'm not sure it's much faster. : ?

This means we'll save on a node_build_content() and drupal_render() on node form submission where Mollom isn't needed anyways.