Update to 1.8.6, set LICENSE.

Overview of changes from pycairo 1.8.4 to pycairo 1.8.6
=======================================================

Bug Fixes:
    ImageSurface.create_from_png _read_func fix
    ToyFontFace type fix
    19221: restore cairo.Matrix '*' operator to the way it originally worked.

Other Changes:
    Documentation completed.

(wiz)