Moving a bunch of css3 border-image and background-size
tests into their better and more appropriate
css-backgrounds-3 folder(s); their associated
reference files and support files should
have been moved or copied and appropriatedly
linked.

--HG--
rename : css21/background-size-cover-contain-001.xht => css-backgrounds-3/background-size/background-size-cover-contain-001.xht
rename : css21/background-size-cover-contain-002.xht => css-backgrounds-3/background-size/background-size-cover-contain-002.xht
rename : css21/support/200x200-red.png => css-backgrounds-3/background-size/support/200x200-red.png
rename : css21/support/50x50-green.png => css-backgrounds-3/background-size/support/50x50-green.png
rename : css21/border-image-017.xht => css-backgrounds-3/border-image-017.xht
rename : css21/border-image-018.xht => css-backgrounds-3/border-image-018.xht
rename : css21/border-image-019.xht => css-backgrounds-3/border-image-019.xht
rename : css21/border-image-020.xht => css-backgrounds-3/border-image-020.xht
rename : css21/border-image-slice-001.xht => css-backgrounds-3/border-image-slice-001.xht
rename : css21/border-image-slice-002.xht => css-backgrounds-3/border-image-slice-002.xht
rename : css21/border-image-slice-003.xht => css-backgrounds-3/border-image-slice-003.xht
rename : css21/support/outline-5px-10px-15px-20px-green.png => css-backgrounds-3/support/outline-5px-10px-15px-20px-green.png