evaluate-seqs: replace histograms with scatterplot of similarity X coverage X abundance

[nbokulich]

Improvement Description
Replace (or supplement) histograms of mismatches X count with similarity X coverage X abundance

Current Behavior
Histograms of mismatches X count are less effective if reads have different lengths (and hence mismatches indicate different % similarity)

Proposed Behavior
Replace or supplement with a better plot (see forum link below)

References
forum xref