ensure that fixed[st]iafpars are defined when exiting for optim.args=NULL

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/surveillance@728 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
avoid warning when conf.type=NULL in iafplot()

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/surveillance@729 edb9625f-4e0d-4859-8d74-9fd3b1da38cb