[Devel] FT 1.x updated to OpenType 1.3

[Werner LEMBERG]

Dear friends,


I've updated GPOS and GSUB support to OpenType 1.3 -- this also fixes
a problem with cursive connections (there were incorrect vertical
offsets).

. OT 1.3 reintroduced the RIGHT_TO_LEFT lookup flag (but with a new
  meaning).  A new member `first' has been added to the GPOS_Instance
  structure; it marks the beginning of a chain of valid cursive connections.
  If the chain has ended, and if this flag is set, all vertical offsets are
  shifted upwards so that the last glyph of the chain is on the baseline.

. Extension lookups (for both GSUB and GPOS) are now implemented.

Please test.  Attached are two images, showing a string with the font
msfarsi.ttf.  `arabic_new.png' should be the right one (produced with
the new code) -- can someone validate this?  My knowledge of cursive
Arabic scripts is nonexistent.


    Werner