force PA.nb.rep to be positive if PA.strategy is defined

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/biomod@653 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
remove force PA.nb.rep to be positive if PA.strategy is defined

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/biomod@654 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
enable ensemble forecasting models selection


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/biomod@655 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
update NEWS file

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/biomod@656 edb9625f-4e0d-4859-8d74-9fd3b1da38cb