LCD filtering changes

[Alexei Podtelezhnikov]

Hi all,

>From  https://gitlab.freedesktop.org/freetype/freetype/-/merge_requests/413

  - Several  changes  related  to  LCD  filtering  are implemented  to
    achieve better performance and encourage sound practices.

    . Instead of  blanket LCD filtering over the entire bitmap,  it is
      now applied only to non-zero spans using direct rendering.  This
      speeds up the ClearType-like rendering by more than 40% at sizes
      above 32 ppem.

    . Setting the filter weights with FT_Face_Properties  is no longer
      supported.  The default and light filters  are optimized to work
      with any face.

    . The legacy libXft LCD filter algorithm is no longer provided.

Please comment here or on the merge request.

Thanks
Alexei