ft2font module-level constants replaced by enums
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The `.ft2font`-level constants have been converted to `enum` classes, and all API using
them now take/return the new types.

The following constants are now part of `.ft2font.Kerning` (without the ``KERNING_``
prefix):

- ``KERNING_DEFAULT``
- ``KERNING_UNFITTED``
- ``KERNING_UNSCALED``

The following constants are now part of `.ft2font.LoadFlags` (without the ``LOAD_``
prefix):

- ``LOAD_DEFAULT``
- ``LOAD_NO_SCALE``
- ``LOAD_NO_HINTING``
- ``LOAD_RENDER``
- ``LOAD_NO_BITMAP``
- ``LOAD_VERTICAL_LAYOUT``
- ``LOAD_FORCE_AUTOHINT``
- ``LOAD_CROP_BITMAP``
- ``LOAD_PEDANTIC``
- ``LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH``
- ``LOAD_NO_RECURSE``
- ``LOAD_IGNORE_TRANSFORM``
- ``LOAD_MONOCHROME``
- ``LOAD_LINEAR_DESIGN``
- ``LOAD_NO_AUTOHINT``
- ``LOAD_TARGET_NORMAL``
- ``LOAD_TARGET_LIGHT``
- ``LOAD_TARGET_MONO``
- ``LOAD_TARGET_LCD``
- ``LOAD_TARGET_LCD_V``

The following constants are now part of `.ft2font.FaceFlags`:

- ``EXTERNAL_STREAM``
- ``FAST_GLYPHS``
- ``FIXED_SIZES``
- ``FIXED_WIDTH``
- ``GLYPH_NAMES``
- ``HORIZONTAL``
- ``KERNING``
- ``MULTIPLE_MASTERS``
- ``SCALABLE``
- ``SFNT``
- ``VERTICAL``

The following constants are now part of `.ft2font.StyleFlags`:

- ``ITALIC``
- ``BOLD``
