clarified and simplified usage of permanent magnet losses in Electrical.Machines and FundamentalWave (no backwards compatibility problems, since permanent magnet losses were introduced in MSL 3.2.1 [current trunk])

git-svn-id: https://svn.modelica.org/projects/Modelica/trunk@6093 7ce873d0-865f-4ce7-a662-4bb36ea78beb