[Enh] Make axis limits for scatterplots configurable

[hlmore]

Currently Beaverdam forces scatterplots to include (0,0), regardless of the range of the data. This is not appropriate for all datasets and can make the plot difficult to read. Manually zooming in on the plot doesn't solve the problem, because the axis limits are reset to include (0,0) each time a filter is applied. It would be nice to have an option in the config file to specify whether axis limits should autoscale to fit the data, or whether they should include (0,0).