Add edge-neon GEGL Port

    Ports edge-neon to GEGL. Current implementation is not the most
    efficient, but it matches the output from the GIMP Filter menu, provided
    that the Gamma-Hack is enabled. Optimizations to follow.

    Current methodology is slow and will need to be adjusted. Excess calls are
    made and the Gaussian separability is not yet enabled.

    https://bugzilla.gnome.org/show_bug.cgi?id=697876