Modified barchart in species inspector panel to look like NetLogo histogram.

Variations that are not selected will have zero values. There will only be as
many bars are selected variations.
Made barcharts to look more like NetLogo histogram (with gaps)

If at least one variation is selected, a bar for that variation(s) is
shown along with gaps for other non-selected variations. This makes
the bar chart look more like NetLogo Histograms.