Reconsider color map for phred qualities #214
Description
Currently a diverging color map is used marking some scores as "bad" (red), "neutral" (white) and "good" (blue). However what is "bad" and not "bad" is up for interpretation. Maybe a less opinionated colormap should be used?
Maybe it should be user-settable scale where the diverging point should be set? If the point is set at 0 it will be a uniform gradient of blue, as I know at least one person prefers.
I like the current implementation, but I am open to suggestions.