• [merge] Merge GDEF marksets in Lookups properly (#2474).
• [feaLib] Have fontTools feaLib script exit with error code when build fails (#2459)
• [svgPathPen] Added ntos option to customize number formatting (e.g. rounding) (#2471).
• [subset] Speed up subsetting of large CFF fonts (#2467).
• [otTables] Speculatively promote lookups to extension to speed up compilation. If the offset to lookup N is too big to fit in a ushort, the offset to lookup N+1 is going to be too big as well, so we promote to extension all lookups from lookup N onwards (#2465).