gui_toolkit 0.75.0

Changed

• Slug glyph data built in half the time: slug_build sorts the curves of an axis once (one u64 key each) and puts each curve in the bands it spans, found from its bounds against the bands' own; it sorted the curves of every band and tested every curve against every band of each of the ten band counts it tries. The same data (test slug bands_are_their_definition); 400 glyphs of a face, best of 5: Segoe UI 5.5 -> 2.8 ms, Times New Roman 8.3 -> 3.9 ms, Nirmala UI 10.0 -> 4.6 ms.