Add DcMotor model

[jevontech]

I am planning to add a DcMotor component composed of existing components to the library.
What would be the most appropriate location?
I was thinking of adding a new toplevel module ElectroMechanical (with submodules for Rotational and Translational?), but for example the EMF model is now located in Electrical.
Any suggestions ?

[ChrisRackauckas]

Hey, is this going to be a more sophisticated DC motor model or is it going to be similar to one like the Modelica standard library?

[jevontech]

I want to start with the basic DC motor model as used in the ModelingToolkitStandardLibrary example and then build other models later on. For now I will put them in my own library elan8/Elan8ComponentLibrary.jl