Merge AC.OnePhase revisions

Merge revisions of AC.OnePhase and some of its base classes.

See also https://github.com/lbl-srg/modelica-buildings/issues/274 and various `fixme` that I added to the code.

I run out of time to run the unit tests. It is possible that some models (also in other packages) do not work as I renamed `linear` to `linearized` and made a few variables and instances protected as I don't think users are interested in the results of the them.