Optionally build web-extension*.lisp

[Ambrevar]

Currently the web-extension*.lisp files are built into the default binary, while the library support is not built by default.

This is inconsistent and GTK should not depend so strongly on web-extensions.

I propose to add a feature macro to toggle the web-extension dependency in gtk.lisp.

Maybe better: Leverage more of CLOS and have a gtk-with-web-extension renderer.

[aartaka]

This is inconsistent and GTK should not depend so strongly on web-extensions.

For sure, yes. I think that we should add as much on-signal-* methods and thus decouple Nyxt side from the FFI port. on-signal-* methods are part of our FFI anyway (maybe move them to foreign-interface.lisp?)

I propose to add a feature macro to toggle the web-extension dependency in gtk.lisp.

That'd work too, but I'd rather decouple it in a different way :)

Maybe better: Leverage more of CLOS and have a gtk-with-web-extension renderer.

That's an option too, yes.