[pca] auto update for develomp

[Martin Paul]

Hi Paul,

> If I wanted to run the development version of pca and keep it up to date
> with the latest version, is there an option for that?

Setting the "pcaurl" option (as you already mentioned below) is the 
supported and documented way to do that. If the URL should ever change, 
I would put a redirect in place so the URL is kept valid. With 
"update=develop" I would have to hardcode the URL into pca, which 
doesn't give any advantage either.

If there's any other disadvantage to setting pcaurl which I don't see, 
please let me know.

> You could even have the dev version look for pca-dev.conf, but that may
> start to complicate things.

Yes, even though I'm working with different versions of pca a lot, I've 
never needed that.

Martin.