Box plots with no data no longer attempt to draw with NaN values at the top of the graph

This also makes elasticX true by default for box plots. Otherwise the animations for a box plot that is filtered out are confusing (as that box will jump to the box after it). It also seems strange to have an entirely blank portion of the graph.

We also noticed that boxplot modifies the underlying data by adding a map function to each data point. You pointed out earlier that this was undesirable. Should this be changed?