suggested changes in letter

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@563 255f4249-2263-4417-b1ea-8498779e27a7
are -> were

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@564 255f4249-2263-4417-b1ea-8498779e27a7
fix sctest

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@565 255f4249-2263-4417-b1ea-8498779e27a7
added sctest() explanations for ctree



git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@566 255f4249-2263-4417-b1ea-8498779e27a7
added some comments in NEWS

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@567 255f4249-2263-4417-b1ea-8498779e27a7