numerator cutoff is slightly off in proportion_plot

[mortonjt]

From this forum post: https://forum.qiime2.org/t/gneiss-picking-up-of-meaningful-balances/8909/5

It looks like the numerator / denominator cutoff is slightly off -- here Bifidobacter should be in denominator - but in the plot, it looks like it is in the numerator.

[justinshaffer]

@mortonjt - Thanks! If this is directly related to the dark- vs. light-blue shading cutoff in the plot, it is a bit misleading and I think should be fixed. In the example provided, it looks like 11/20 taxa are binned into light-blue (numerator) whiel only 9/20 into dark-blue (denominator). Probably a [simple] fix with the cutoff for inclusion in either dark- vs. light-blue?

CC: @fedarko

[fedarko]

@mortonjt Justin and I think we may have narrowed the problem down to around this region of q2-gneiss' codebase. The comment about "overriding the default colors in the numerator / denominator" seems a bit suspicious.