changed similarity law implementation of Buildings.Fluid.Movers.BaseClasses.Characteristics.power :
1) Similarity law now uses a working point based on a reduced rotational speed V_flow/r_N instead of V_flow. Only when referring to this working point then the power law P2= r_N^3*P1 is valid.
2) The power 3 described above has been reduced to 2.75 to better match real working characteristics from pumps. This can be explained by the idea that the electrical part of the pump (motor) does not follow the similarity law and that its efficiency generally increases for higher powers.
Merge branch 'master' of github.com:lbl-srg/modelica-buildings