dredge: more meaningful warning message about misspecified 'fixed' argument. 
pdredge: synchronized code with 'dredge'
documentation: fixed formatting issues


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mumin@271 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
deleted old packages

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mumin@272 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
documentation: nicer formating of R^2
print.summary.model.avg: restored lost significance stars

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mumin@273 edb9625f-4e0d-4859-8d74-9fd3b1da38cb