Fcircle(Inf) is finite if d > 2; used in R0(, trimmed=FALSE)

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/surveillance@719 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
let R0() only output message about non-finite R0 values if they really are

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/surveillance@720 edb9625f-4e0d-4859-8d74-9fd3b1da38cb