Color aggregate lines the same across versions

[jonco3]

At present it can be confusing looking at evolution graphs because the individual aggregates get assigned different line colors for different versions, e.g.:

I'm not sure whether that's exactly what this issue is talking about but it may be: #625

These changes fix this by removing the version component from Line.getStateString and renaming it to Line.getColorId (this is the only use of that method).

[chutten]

I do indeed believe that this is #625

We might not wish to do this for the submission date view, as the same submission date can have multiple versions (the same x value can have multiple data points) for a single aggregate. See, for instance this.

How bad would it look in the code if we only turned to this mode for submission date view?

[chutten]

Let me know what you think about my earlier comment.