[RobAStBase] interpolRisks gain biastype and normtype methods

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/robast@760 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
[RobAStBase] argh a typo with biastype and normtype methods of interpolRisks.R 

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/robast@761 edb9625f-4e0d-4859-8d74-9fd3b1da38cb