 * \[**Breaking**\] Change the mechanism of variants of not-equal ligation (#1400):
   - The "dotted" ligation groups (`exeqeq-dotted`, `eqexeq-dotted`, `eqexeq-dl-dotted`, `exeq-dotted`) are removed.
   - A character variant, "lig-neq" (feature tag `VXAF`), is added to control the shape instead.
 * Ensure that the middle point between Typo Ascender and Descender lies on the middle of symbols/operators (#1398).
