Adapted estimator.nleqslv in order to function with nleqslv version 2.4 and cleaned up vignettes.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/pim@39 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Cleanup pim package for functioning with nleqslv version 2.4

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/pim@40 edb9625f-4e0d-4859-8d74-9fd3b1da38cb