• [varLib] Make sure that fvar named instances only reuse name ID 2 or 17 if they are at the default location across all axes, to match OT spec requirement (#3831).
• [feaLib] Improve single substitution promotion to multiple/ligature substitutions, fixing a few bugs as well (#3849).
• [loggingTools] Make Timer._time a static method that doesn't take self, makes it easier to override (#3836).
• [featureVars] Use None for empty ConditionSet, which translates to a null offset in the compiled table (#3850).
• [feaLib] Raise an error on conflicting ligature substitution rules instead of silently taking the last one (#3835).
• Add typing annotations to T2CharStringPen (#3837).
• [feaLib] Add single substitutions that were promoted to multiple or ligature substitutions to aalt feature (#3847).
• [featureVars] Create a default LangSys in a ScriptRecord if missing when adding feature variations to existing GSUB later in the build (#3838).
• [symfont] Added a main().
• [cffLib.specializer] Fix rmoveto merging when blends used (#3839, #3840).
• [pyftmerge] Add support for cmap format 14 in the merge tool (#3830).
• [varLib.instancer/cff2] Fix vsindex of Private dicts when instantiating (#3828, #3232).
• Update text file read to use UTF-8 with optional BOM so it works with e.g. Windows Notepad.exe (#3824).
• [varLib] Ensure that instances only reuse name ID 2 or 17 if they are at the default location across all axes (#3831).
• [varLib] Create a dflt LangSys in a ScriptRecord when adding variations later, to fix an avoidable crash in an edge case (#3838).