message: Add vertical metrics table
diff: @@ -266,7 +266,7 @@ FontTable (tag : Tag) (length : U32) = match tag.value {
  "PCLT" => Pcl5, // PCL 5 data
  "VDMX" => VerticalDeviceMetrics, // Vertical device metrics
  "vhea" => VerticalHeader, // Vertical Metrics header
  - "vmtx" => Unknown, // Vertical Metrics
  + "vmtx" => Unknown, // Vertical Metrics // TODO: Depends on `num_glyphs` from "maxp" and `num_of_long_vertical_metrics` from "vhea"
  _ => Unknown,
  };
  @@ -4659,9 +4659,22 @@ struct VerticalHeader_1_1 {
  //
  // vmtx - Vertical Metrics Table
  //
  -// <https://www.microsoft.com/typography/otspec/vmtx.htm>
  +// <https://docs.microsoft.com/en-us/typography/opentype/spec/vmtx>
  // <https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6vmtx.html>
  //
  // =============================================================================
  +struct VerticalMetrics (num_glyphs : U16) (num_of_long_vertical_metrics : U16) {
  + entries : Array num_of_long_vertical_metrics VerticalMetricsEntry,
  + /// The top sidebearing of the glyph. Signed integer in FUnits.
  + top_side_bearing : Array (nat_sub num_glyphs num_of_long_vertical_metrics) S16Be,
  +};
  +
  +struct VerticalMetricsEntry {
  + /// The advance height of the glyph. Unsigned integer in FUnits
  + advance_height : U16Be,
  + /// The top sidebearing of the glyph. Signed integer in FUnits.
  + top_side_bearing : S16Be,
  +};
  +
  // TODO
  