[Draft]: Add missing tables to OpenType definition

[archaephyrryx]

Missing Tables in Extant Implementation

Current Slate

• prep
• gasp
• BASE
• GDEF
• GPOS
• GSUB
• JSTF
• MATH

Deliberately Deferred

• CFF
• CFF2
• VORG

Low Priority

• SVG
• EBDT
• EBLC
• EBSC
• CBDT
• CBLC
• sbix

Metrics (out of 659 fonts)

    516 [MISSING IMPL]: `GDEF`
    490 [MISSING IMPL]: `GSUB`
    472 [MISSING IMPL]: `GPOS`
    238 [MISSING IMPL]: `CFF20`
    132 [MISSING IMPL]: `DSIG`
     90 [MISSING IMPL]: `FFTM`
     77 [MISSING IMPL]: `hdmx`
     70 [MISSING IMPL]: `VDMX`
     66 [MISSING IMPL]: `LTSH`
     54 [MISSING IMPL]: `kern`
     29 [MISSING IMPL]: `PCLT`
     29 [MISSING IMPL]: `BASE`
     27 [MISSING IMPL]: `TSIa9`
     20 [MISSING IMPL]: `STAT`
     19 [MISSING IMPL]: `vmtx`
     19 [MISSING IMPL]: `vhea`
     19 [MISSING IMPL]: `TSI0`
     18 [MISSING IMPL]: `TSI1`
     17 [MISSING IMPL]: `TTFA`
     16 [MISSING IMPL]: `fvar`
     15 [MISSING IMPL]: `SVG20`
     15 [MISSING IMPL]: `HVAR`
     15 [MISSING IMPL]: `EBLC`
     15 [MISSING IMPL]: `EBDT`
     14 [MISSING IMPL]: `gvar`
     13 [MISSING IMPL]: `VORG`
     10 [MISSING IMPL]: `TSI4`
     10 [MISSING IMPL]: `TSI2`
      9 [MISSING IMPL]: `TSI5`
      8 [MISSING IMPL]: `MVAR`
      6 [MISSING IMPL]: `mort`
      6 [MISSING IMPL]: `meta`
      6 [MISSING IMPL]: `CFF2`
      6 [MISSING IMPL]: `avar`
      5 [MISSING IMPL]: `BDF20`
      4 [MISSING IMPL]: `JSTF`
      3 [MISSING IMPL]: `TSIV`
      3 [MISSING IMPL]: `Sill`
      3 [MISSING IMPL]: `Silf`
      3 [MISSING IMPL]: `MTfn`
      3 [MISSING IMPL]: `Gloc`
      3 [MISSING IMPL]: `Glat`
      3 [MISSING IMPL]: `Feat`
      2 [MISSING IMPL]: `morx`
      2 [MISSING IMPL]: `MATH`
      2 [MISSING IMPL]: `feat`
      2 [MISSING IMPL]: `CBLC`
      2 [MISSING IMPL]: `CBDT`
      1 [MISSING IMPL]: `TSIS`
      1 [MISSING IMPL]: `TSIP`
      1 [MISSING IMPL]: `TSID`
      1 [MISSING IMPL]: `Silt`
      1 [MISSING IMPL]: `sbix`
      1 [MISSING IMPL]: `PfEd`
      1 [MISSING IMPL]: `MERG`
      1 [MISSING IMPL]: `cvar`
      1 [MISSING IMPL]: `CPAL`
      1 [MISSING IMPL]: `COLR`
      1 [MISSING IMPL]: `bloc`
      1 [MISSING IMPL]: `bdat`