Revert Graphite support

This reverts commits:

  306ad4e93be12de8394f7c0c177ca3f9c4e3b836
  02014624b99b90785077deedc905cba02d517c52
  19a6fb59296200ccb0a1389bb3926c9c0f70761b

Will be handled with the table action call back.

Related to #15
Add user callback to decide what to do with tables

Fixes #15
[ot-sanitise] Keep Graphite tables

Serves also as a way to test the table action callback.
Simplify a bit
Make it possible to passthru required tables

Not entirely sure if it is a good idea, but we can revert it if we think
it is not.

Related to #15
Parse language of cmap subtables

And use it when checking subtable order. Fixes #16, though the cmap
table of the font in question is still rejected because we don’t support
parse format 6 subtables.
Make this message actually useful