Implement GPOS/GSUB Lookup Tables

[Dalgona]

Part of this description was taken from neodgm/neodgm#12.

GPOS

• Lookup Type 1: Single Adjustment Positioning
  • Format 1: Single Positioning Value
  • Format 2: Array of Positioning Values
• Lookup Type 2: Pair Adjustment Positioning
  • Format 1: Adjustments for Glyph Pairs
  • Format 2: Class Pair Adjustment
• Lookup Type 3: Cursive Attachment Positioning
  • Format 1: Cursive Attachment
• Lookup Type 4: Mark-to-Base Attachment Positioning
  • Format 1: Mark-to-Base Attachment Point
• Lookup Type 5: Mark-to-Ligature Attachment Positioning
  • Format 1: Mark-to-Ligature Attachment
• Lookup Type 6: Mark-to-Mark Attachment Positioning
  • Format 1: Mark-to-Mark Attachment
• Lookup Type 7: Contextual Positioning
  • Format 1: Simple Glyph Contexts
  • Format 2: Class-based Glyph Contexts
  • Format 3: Coverage-based Glyph Contexts
• Lookup Type 8: Chaining Contextual Positioning
  • Format 1: Simple Glyph Contexts
  • Format 2: Class-based Glyph Contexts
  • Format 3: Coverage-based Glyph Contexts
• Lookup Type 9: Extension Positioning
  • Format 1

Shared Tables

• Value Record
• Anchor Table
• Mark Array Table

GSUB

• Lookup Type 1: Single Substitution
  • Format 1: Many to one delta
  • Format 2: One to one
• Lookup Type 2: Multiple Substitution
  • Format 1
• Lookup Type 3: Alternate Substitution
  • Format 1
• Lookup Type 4: Ligature Substitution
  • Format 1
• Lookup Type 5: Contextual Substitution
  • Format 1: Simple Glyph Contexts
  • Format 2: Class-based Glyph Contexts
  • Format 3: Coverage-based Glyph Contexts
• Lookup Type 6: Chained Contexts Substitution
  • Format 1: Simple Glyph Contexts
  • Format 2: Class-based Glyph Contexts
  • Format 3: Coverage-based Glyph Contexts
• Lookup Type 7: Extension Substitution
  • Format 1
• Lookup Type 8: Reverse Chaining Contextual Single Substitution
  • Format 1