• [ufoLib] Reverted accidental method name change in UFOReader.getKerningGroupConversionRenameMaps
  that broke compatibility with downstream projects like defcon (#3948, #3947, robotools/defcon#478).
• [ufoLib] Added test coverage for getKerningGroupConversionRenameMaps method (#3950).
• [subset] Don't try to subset BASE table; pass it through by default instead (#3949).
• [subset] Remove empty BaseRecord entries in MarkBasePos lookups (#3897, #3892).
• [subset] Add pruning for MarkLigPos and MarkMarkPos lookups (#3946).
• [subset] Remove duplicate features when subsetting (#3945).
• [Docs] Added documentation for the visitor module (#3944).