v6.12.7

• _is_vertical() now checks for vhea custom parameters (vheaVertAscender,
  vheaVertDescender, vheaVertLineGap) at the font/master level, not just per-glyph
  vertWidth/vertOrigin. Previously this caused vmtx tables with all-zero advance
  heights (PR #1133, fixes #1132).
• Smart component anchors are now interpolated during propagation, fixing incorrect
  anchor positions (PR #1131).
• Fix detection of cursive anchors with suffixes (e.g. entry.ltr). The prefix check
  was matching the end of the name instead of the beginning (PR #1130).
• Parse and serialize the GSGlyph.locked property, which was previously lost on
  round-trip (PR #1128).
• Fix reading GSPath attributes by explicitly setting the parser type to dict,
  preventing type contamination from previously parsed objects (PR #1126, fixes #1124).
• Propagate the hidden axis attribute when converting between Glyphs and
  designspace formats, so fvar HIDDEN_AXIS flag is set correctly (PR #1123).
• Remove duplicate long-form custom parameter names that were already covered by
  short-name aliases (PR #1120).
• Serialize GSInstance.type generically instead of hard-coding VARIABLE, to be
  forward-compatible with potential new instance types (PR #1127).