Pathway Bar plot should include the possibility of having multiple bars for each gene. #4

In the case in which someone has more than binary experimental conditions, a "case, normalized to control" signal for each gene is insufficient. Imagine an experiment in which someone wants to understand combinatorial experimental variables, e.g. `AB` vs `Ab` vs `aB` vs `ab`. Perhaps 3 bars per gene with `AB`, `Ab`, and `aB` all normalized against `ab` would be interesting. Perhaps something else. Generally speaking, it should be possible to plot multiple bars per gene, given a suitable data structure.