[OGDev] Recent Changes page

[Kake L Pugh]

Hello.  I was thinking that it might be a good idea if, where a guide
hasn't been edited in the past month, the Recent Changes page shows
all edits in the past 6 months instead.  The reasoning behind this is
that for a low-traffic guide, a month isn't actually all that long,
and that a blank Recent Changes page looks broken.

An alternative might be to show the last n edits instead of hardcoding
to 6 months, but that's inconsistent with the normal Recent Changes output.

In the long term, I'd like to make Recent Changes much more
customisable, but in the short term this is a quick fix which would go
a long way towards making the lower-traffic guides look better.

Thoughts?

Kake