changes to thermostatic3wayValve:
1) added conditional state and initial condition for k
2) added parameters for limit values of k
replace thermostatic threewayvalve by a valve motor with PI Controller.
change the Thermostatic3WayValve for one using a PI controller.
Merge remote-tracking branch 'remotes/upstream/issue111_3wayValve' into issue108_HeatingSystems
filter the input of pump in Heating_Embedded_DHW_STS.mo