• [varLib.instancer] Added support for L4 instancing, i.e. moving the default value of an axis while keeping it variable. Thanks Behdad! (#2728, #2861).
  It's now also possible to restrict an axis min/max values beyond the current default value, e.g. a font wght has min=100, def=400, max=900 and you want a partial VF that only varies between 500 and 700, you can now do that. You can either specify two min/max values (wght=500:700), and the new default will be set to either the minimum or maximum, depending on which one is closer to the current default (e.g. 500 in this case). Or you can specify three values (e.g. wght=500:600:700) to set the new default value explicitly.
• [otlLib/featureVars] Set a few Count values so one doesn't need to compile the font to update them (#2860).
• [varLib.models] Make extrapolation work for 2-master models as well where one master is at the default location (#2843, #2846).
  Add optional extrapolate=False to normalizeLocation() (#2847, #2849).
• [varLib.cff] Fixed sub-optimal packing of CFF2 deltas by no longer rounding them to integer (#2838).
• [scaleUpem] Calculate numShorts in VarData after scale; handle CFF hintmasks (#2840).