This commit adds two fallback scripts (`latb', `latp') and
implements support for the no-base character ranges introduced in
the previous commit.
* src/autofit/aftypes.h (AF_ScriptClassRec): Add
`script_uni_nobase_ranges' field.
(AF_DEFINE_SCRIPT_CLASS): Updated.
* src/autofit/afscript.h, src/autofit/afstyles.h: Add `latb' and
`latp' fallback scripts.
* src/autofit/afblue.dat: Add blue zones for Latin subscript and
superscript fallback scripts.
* src/autofit/afblue.c, src/autofit/afblue.h: Regenerated.
* src/autofit/afglobal.h (AF_NOBASE): New style flag for no-base
characters.
(AF_STYLE_MASK): Updated.
* src/autofit/afglobal.c (SCRIPT): Updated.
(af_face_globals_compute_style_coverage): Handle new style flag.
* src/autofit/aflatin.c (af_latin_hints_apply): Handle new style
flag.
* src/autofit/afranges.h (SCRIPT): Use it to export no-base ranges.