add three demos:
- identify-positive-substrates.R
- compare-phenotype-genotype-similarity.R
- distinguish-curve-topologies.R

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/opm@525 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
next try, this time with checking the demos using check_R_code()

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/opm@526 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
minor additions to keep track with uploads


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/opm@527 edb9625f-4e0d-4859-8d74-9fd3b1da38cb