[development] update span

[Khalid B]

> > We should not include more updates than one version: from 4.5 to
> > 4.6 , from 4.6 to 4.7 . Thoughts? Experience with jumping two
> > versions?

Some time back, I upgraded a client from 4.3 (or was it 4.2? Can't remember)
to 4.6. I had to do some manual work, mainly see where things fail and do the
ALTERs ...etc. by hand. It was all OK at the end, and the site runs fine now.

Of course, as always, I took a copy of the database, and files, and did the
upgrade on it first.

Requiring people to update  from X to X+1 to X+2 then to X+3 is a pain, and
I would rather not go that route at all.