rename Image.ANTIALIAS to Image.LANCZOS
new section framework
chapters:
Antialias renamed to Lanczos
Default filter for thumbnails
Image transposing
chapters:
Image resizing filters
Bicubic and Bilinear downscaling
Lanczos upscaling quality
Bicubic upscaling quality
chapters:
Resize performance
Gaussian blur and unsharp mask chapters
fix spelling
Merge pull request #1032 from homm/release-notes

Release notes for 2.7
Merge pull request #1028 from homm/resize-constants

Rename Image.ANTIALIAS to Image.LANCZOS