graph display with graphviz. git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1210 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
aggregate averages. git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1209 b08c6af1-5177-4d33-ba66-4b1c6b8b522a