Physical inputs/outputs

[JortGroen]

In order to identify physical problems from yaml configurations, we propose to introduce a distinction between data ports and physical ports.
Physical ports is an input/output that represents a physical flow (e.g., electricity, biomass, H2, etc.).

The problem with the way the ports are now configured is, is that it allows replication of these connections,e.g., an input representing a physical output is connected to two different models. The value of the output is then copied to both inputs. This would mean that the physical thing gets doubled (power output gets doubled because the output value (2W) is fed to two inputs).

In general, the Illuminator cannot currently properly simulate a physical layer because there is always a need for a sink (the grid) which is not implemented by default.

We propose to introduce a distinction between data ports and physical ports, such that we can subject physical connections to physics.

[JortGroen]

new idea emerged to use states for non-physical connections. See discussion #113