updated 'cg.sde.pseudodata'

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/colgem@47 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
added require(data.table) to 'calculate.cluster.size.moments.from.tree'

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/colgem@48 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
last commit was supposed to be in 'calculate.cluster.size.distr.from.tree'

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/colgem@49 edb9625f-4e0d-4859-8d74-9fd3b1da38cb