Fix vlines in hist-function

The vertical lines you get when using the vlines option in the histogram function have different heights. They are linearly increasing or decreasing when plotting a bunch of them. This is confusing and should be fixed.

assigned to @fsauerbu

added Component::Plotting EM::D Type::Bug labels

Here is an example using toy data

The bug is present in the main plot and the ratio plot.

mentioned in merge request !59 (merged)

created merge request !59 (merged) to address this issue

closed via merge request !59 (merged)