Solved a bug caused by argument checking of subset() within diffAmova() when  do.pairwisePhiST=TRUE as reported by Eamonn B. Mallon

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/msap@46 edb9625f-4e0d-4859-8d74-9fd3b1da38cb