Corrects the warning given for algo.rki, algo.rogerson and algo.hmm which said "algo.cdc blablabla" instead of algo.rki etc.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/surveillance@776 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
- twinstim():
  + more informative error message including current siafpars
  + set environment also for returned list in case optim.args=NULL
- document local non-differentiability of lagged power law
- clarified documentation of update.twinstim wrt specifying start values


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/surveillance@777 edb9625f-4e0d-4859-8d74-9fd3b1da38cb