Moved 3 margin collapsing tests, 1 max-width and
1 max-height-max-width tests to better, more
appropriate folders along with their associated
reference file and/or support files.

--HG--
rename : css21/margin-collapse-039.xht => css21/margin-padding-clear/margin-collapse-039.xht
rename : css21/margin-collapse-040.xht => css21/margin-padding-clear/margin-collapse-040.xht
rename : css21/margin-collapse-041.xht => css21/margin-padding-clear/margin-collapse-041.xht
rename : css21/max-height-max-width-001.xht => css21/normal-flow/max-height-max-width-001.xht
rename : css21/max-width-110.xht => css21/normal-flow/max-width-110.xht
rename : css21/support/green200x200.png => css21/normal-flow/support/green200x200.png