LineToAxis annotation handles non-zero origin

[#42212947] In cases where the Y-axis minimum value was positive, e.g. 80, this LineToAxis annotation would run down below the axis to where the nominal location of "0" would be if the graph went that far. This change uses the minimum (or, where appropriate, maximum) value rather than sticking to 0, and also handles quadrants other than the first (i.e. graphs with negative numbers) more reliably.