Lighten the insert process of a new group

Spaces og does a spaces_load for the space that is currently being inserted, witch can cause various caches to be caught too early (for example cck's field caches) and generally expansive. It also calls og_update_group, again, cause og already called it but it needed to change the value.

It's uglier, but instead of that can calculate what those values will be in 'presave', and work around the spaces_load with direct queries.

* Patch is against patches spaces_og, so contains some logic from other patches.
* I don't expect a version of this patch to ever go into spaces-6.x-3.x; too much chance for some horrid conflicts and generally skipping api's like is done is a bad idea.
* Makes the update process a bit heavier.