Integrate with OG spaces presets

At OpenScholar, we're using og_tasks to automate common standard site structures when virtual sites are created. A virtual site is an organic group and a spaces preset. We want to ensure that only specified tasks from our spaces presets features export are available to these group nodes.

To do that, we're submitting a patch to modify the behavior of og_tasks_get_all_tasks() when spaces is enabled and tasks are included in the entity's preset. If these conditions are met, then only the specified tasks are added to the return value.