[dev] [surf] Adblock and custom script loading for surf

Hi,

I implemented custom script loading for surf. This allows to easy implement
adblocking for surf or loading custom scripts per site or page. At the
moment it is a bit hacky. I modified the adblock script from uzbl and
extended it by using CSS selectors to block elements instead of using XPath
to do this (although this makes it a bit slower). It also contains a script
to fetch adblock lists and convert them to a format which is used by
adblock.py. The code is mostly self-explanatory I think.

Constructive criticism and patches are very welcome.

I hope anyone finds this useful, although it is a bit ugly at the moment :)

I attached the patch and a compressed tarball containing the needed
shellscripts.