added confidence interval calculation to multi sample splitting

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/hdi@40 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
added missing step in calculation confidence intervals: taking the median

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/hdi@41 edb9625f-4e0d-4859-8d74-9fd3b1da38cb