Moved 3 padding-related and 1 outline tests to
better, more appropriate folders, as well as
their associated reference files and/or
support images.

--HG--
rename : css21/reference/padding-em-inherit-001-ref.xht => css21/margin-padding-clear/padding-em-inherit-001-ref.xht
rename : css21/padding-em-inherit-001.xht => css21/margin-padding-clear/padding-em-inherit-001.xht
rename : css21/reference/padding-percentage-inherit-001-ref.xht => css21/margin-padding-clear/padding-percentage-inherit-001-ref.xht
rename : css21/padding-percentage-inherit-001.xht => css21/margin-padding-clear/padding-percentage-inherit-001.xht
rename : css21/padding-applies-to-013a.xht => css21/tables/padding-applies-to-013a.xht
rename : css21/reference/outline-layout-006-ref.xht => css21/ui/outline-layout-006-ref.xht
rename : css21/outline-layout-006.xht => css21/ui/outline-layout-006.xht