Fix statistics parsing - columns have moved

Andy,

Please can you review?  A couple of weeks back, I tweaked the sipp scripts because we'd enabled per-user authentication on REGISTERs.  Unfortunately, I didn't spot the stats parsing.  This fix remedies that.

* The first column is before my tweak, so doesn't change.
* The second and third columns are after my tweak, so move ahead by 12 columns.
* The fourth column is also after my tweak, so would move ahead by 12 columns, except its previous position was misleading (it was on the post-call delay, not the receipt of the last message of the call), so I've fixed that up by only moving it forward by 8.

I've tested this live.

Matt