[dev] surf download patch

Hi,

this patch implements a more general approach to http downloading that
doesn't depend on external tools and can cope with resources that are
not easily URI-referenced (for example, for sites like rapidshare with
evil javascript that generates POST requests).

The patch just uses the webkit download feature and shows a customizable
progress page, which is bad old html plus javascript that knows how to deal
with events of the form:

fileinfo(filename, uri, totalsize, currentsize, progress)

So in principle a nice download screen could make your wait more
pleasant, but in practice I suck a lot as a web designer so aware of my
limitations I'm just providing a humble proof-of-concept download.html.
I'll be very thankful if a gentle soul between you retributes me with a
download bar pour la galerie.

Best regards

--
Carlos