AHaumer: start values for integrator states of Blocks.Math.{RectifiedMean, RootMeanSquare, Harmonic} (maintenance 3.2.1 and trunk)

git-svn-id: https://svn.modelica.org/projects/Modelica/branches/maintenance/3.2.1@7280 7ce873d0-865f-4ce7-a662-4bb36ea78beb