[dev] [surf] patch : toggle, horiz scroll, togglestyle

Hi,

I am posting a patch against tip which lies on the border to caprice and
code bloat, but these changes proved very useful to me in the last months.
That's why I'd love to see some of them accepted.

- toggle() boolean properties of Webkit (examples in the config)

- scroll uses a heuristic in passing integer parameter borrowed from
  meillo, I guess, and extended to scroll a page up/down or to the
  begin/end of document. Scrolling vertically and horizontally differs
  just in the GtkAdjustment used. So I've put them together.

  Horizontal scroll is very useful on many (broken) sites when you have a
  small screen.

- setting custom style I found useful for the frequent cases that I read
  long texts of insane color on insane background burning my eyes. The
  style file being sth like * {background:#333333 !important; text:#eeeeee
  !important;}

- the key bindings in the patch are not ok but I ran out of ideas. Couldn't
  post my original ones, since they don't conform to the main line, e.g. I
  have hjkl for scrolling, HL for navigation, gG for begin/end of document,
  Space/Shift|Space for page down/up, etc.

Thanks to everybody contributing to surf.

Hope you find something useful.

cheers,

-- 
 stanio_