internal runifpoint() allows for inner buffer zone without points

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/surveillance@699 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
siaf.step(): added simulation function and optimized code for speed

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/surveillance@700 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
fix variable name in siaf.step()

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/surveillance@701 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
- twinstim allows numeric siaf specification (knots)
- re-organized iaf-help -> new seperate help pages for siaf() and tiaf()


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/surveillance@702 edb9625f-4e0d-4859-8d74-9fd3b1da38cb