Add WPE WebKit HTML5 application runtime.
* libwpe: backend abstraction (Wayland or KMS/DRM)
* wpebackend-fdo: FreeDesktop Linux backend for WPE
* wpewebkit: official WebKit port
* cog: simple browser canvas application (best used with 'cage')
Signed-off-by: Daniel Golle <daniel@makrotopia.org>