Updated freetype2 to 2.7.

Remove subpixel option which is now on by default.

CHANGES BETWEEN 2.6.5 and 2.7

  I. IMPORTANT CHANGES

    - As announced earlier, the 2.7.x series now uses the new subpixel
      hinting  mode as  the  default, emulating  a  modern version  of
      ClearType.

      This change inevitably leads to different rendering results, and
      you  might  change  the  `TT_CONFIG_OPTION_SUBPIXEL_HINTING'
      configuration option to  adapt it to your taste (or  use the new
      `FREETYPE_PROPERTIES'    environment    variable).    See    the
      corresponding entry  below for  version 2.6.4, which  gives more
      information.

    - A new option  `FT_CONFIG_OPTION_ENVIRONMENT_PROPERTIES' has been
      introduced.  If  set (which  is  the  default), an  environment
      variable  `FREETYPE_PROPERTIES' can  be used  to control  driver
      properties.  Example:

        FREETYPE_PROPERTIES=truetype:interpreter-version=35 \
                            cff:no-stem-darkening=1 \
                            autofitter:warping=1

      This allows to select, say, the subpixel hinting mode at runtime
      for a given application.  See file `ftoption.h' for more.

  II. IMPORTANT BUG FIXES

    - After  loading a  named instance  of  a GX  variation font,  the
      `face_index'  value  in  the returned  `FT_Face'  structure  now
      correctly holds the named instance  index in the upper 16bits as
      documented.

  III. MISCELLANEOUS

    - A new macro `FT_IS_NAMED_INSTANCE' to  test whether a given face
      is a named instance.

    - More fixes to GX font handling.

    - Apple's  `GETVARIATION'  bytecode  operator  (needed  for  GX
      variation font support) has been implemented.

    - Another round  of fuzzer fixes,  mainly to reject  invalid fonts
      faster.

    - Handling of raw CID fonts  was broken (bug introduced in version
      2.6.4).

    - The smooth rasterizer has been streamlined  to make it faster by
      approx. 20%.

    - The `ftgrid'  demo program now  understands command  line option
      `-d' to give start-up design coordinates.

    - The `ftdump' demo program has  a new command line option `-p' to
      dump TrueType bytecode instructions.

(wiz)