code standardisation for CRAN submission

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/jbtools@14 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
added function to set missing value attributes

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/jbtools@15 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
code standardisation for CRAN submission

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/jbtools@16 edb9625f-4e0d-4859-8d74-9fd3b1da38cb