README: add link to cl-cffi-gtk
init: push :webkit2 to *features*

So that you can do
(foo)
Add scripts/run_demo
Make use of gobject:define-g-* macros

- Re-define all webkit types with gobject:define-g-object-class.
- Replace all uses of defcenum with gobject:define-g-enum

These macros help ensure correctness and provide sensible
defaults, and export symbols for all class names and accessors
automatically.