[base, smooth] Remove LCD filter from face properties.

This removes the internal face property that sets the filtering weights.
The global filtering algorithms and weights are now optimized to work
well under all conditions.

* include/freetype/internal/ftobjs.h (FT_Face_InternalRec): Do it.
* include/freetype/freetype.h (FT_Face_Properties): Revised docs.
* include/freetype/ftparams.h (FT_PARAM_TAG_LCD_FILTER_WEIGHTS): Ditto.
* src/base/ftlcdfil.c (ft_lcd_padding): Updated.
* src/base/ftobjs.c (ft_open_face_internal, FT_Face_Properties): Ditto.
* src/smooth/ftsmooth.c (ft_smooth_render): Ditto.
* docs/CHANGES: Updated.