Changes:
- apiref.txt has been again revised.
- apirefx.txt has been extended to document the GPOS interface.
- TODO has been dropped (since we consider there will be no
further development).
- TT_Char_Index() now uses TT_ULong for character codes. It now
supports cmap tables in format 8 and 12.
- New error code (TT_Err_Too_Many_FDefs) when a font defines too
many functions.
- Support files for BeOS have been contributed by Chris Herborth.
- The EXPORT_DEF/EXPORT_FUNC/etc. stuff has been replaced with a
more elaborate scheme.
- Cleaning up of the ft_conf.h files to remove obsolete stuff.
- TT_GSUB_Add_String() has two additional parameters needed for
GPOS support.
- TT_CharMap_Next() of the ftxcmap extension now uses `TT_ULong'
as the second parameter.
- A long-lived bug in ftxpost.c.
