Demo-3, building the complete building model,
has compile problem.

Flow network demo does not work
due to major EKS structure change.

Plant: sequential type plant demo needs refinement.
(eg add time/ iterative loop and basic graphics output.

Plant: state-space type plant can be built but
has a run time error.

Classes written but not yet integrated:

   Conduction_steady_state
   Conduction_response_function
   Radiation_short_wave.
