Implement GPOS/GSUB Lookup Tables

[Dalgona]

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

GPOS

• [ ] Lookup Type 1: Single Adjustment Positioning
  • [x] Format 1: Single Positioning Value
  • [ ] Format 2: Array of Positioning Values
• [ ] Lookup Type 2: Pair Adjustment Positioning
  • [ ] Format 1: Adjustments for Glyph Pairs
  • [x] 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
• [x] Lookup Type 7: Contextual Positioning
  • [x] Format 1: Simple Glyph Contexts
  • [x] Format 2: Class-based Glyph Contexts
  • [x] Format 3: Coverage-based Glyph Contexts
• [x] Lookup Type 8: Chaining Contextual Positioning
  • [x] Format 1: Simple Glyph Contexts
  • [x] Format 2: Class-based Glyph Contexts
  • [x] Format 3: Coverage-based Glyph Contexts
• [ ] Lookup Type 9: Extension Positioning
  • [ ] Format 1

Shared Tables

• [x] Value Record
• [ ] Anchor Table
• [ ] Mark Array Table

GSUB

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