fixed bugs in bwlabel3d


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/bioimagetools@109 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
bugfix bwlabel3d


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/bioimagetools@110 edb9625f-4e0d-4859-8d74-9fd3b1da38cb