• [OS/2 / merge] Automatically recalculate OS/2.xAvgCharWidth after merging fonts with fontTools.merge (#2591, #2538).
• [misc/config] Added fontTools.misc.configTools module, a generic configuration system (#2416, #2349).
  Added fontTools.config module, a fontTools-specific configuration system using configTools above.
  Attached a Config object to TTFont.
• [otlLib] Replaced environment variable for GPOS compression level with an equivalent option using the new config system.
• [designspaceLib] Incremented format version to 5.0 (#2436).
  Added discrete axes, variable fonts, STAT information, either design- or user-space location on instances.
  Added fontTools.designspaceLib.split module to split a designspace into sub-spaces that interpolate and that represent the variable fonts listed in the document.
  Made instance names optional and allow computing them from STAT data instead.
  Added fontTools.designspaceLib.statNames module.
  Allow instances to have the same location as a previously defined STAT label.
  Deprecated some attributes:
  SourceDescriptor: copyLib, copyInfo, copyGroups, copyFeatures.
  InstanceDescriptor: kerning, info; glyphs: use rules or sparse sources.
  For both, location: use the more explicit designLocation.
  Note: all are soft deprecations and existing code should keep working.
  Updated documentation for Python methods and the XML format.
• [varLib] Added build_many to build several variable fonts from a single designspace document (#2436).
  Added fontTools.varLib.stat module to build STAT tables from a designspace document.
• [otBase] Try to use the Harfbuzz Repacker for packing GSUB/GPOS tables when uharfbuzz python bindings are available (#2552). Disable it by setting the "fontTools.ttLib.tables.otBase:USE_HARFBUZZ_REPACKER" config option to False. If the option is set explicitly to True but uharfbuzz can't be imported or fails to serialize for any reasons, an error will be raised (ImportError or uharfbuzz errors).
• [CFF/T2] Ensure that pen.closePath() gets called for CFF2 charstrings (#2577).
  Handle implicit CFF2 closePath within T2OutlineExtractor (#2580).