"Fixes" color of answer line for line construction

This uses a hard-wired color for the correct line rather than drawing a color (and thus reserving it) from the activity color pool. [#44476899]
Using a human-readable "name" for calculated line

For [#44476899], this makes the datadef name which shows up in the legend something more friendly than "CorrectLine-1". (We needed to retain the number in case there is more than one line construction sequence in an activity.)
JS compiled from changes
Fixing expected output for tests