Plot Phred score distributions
H = plotPerPositionQuality(QSObj)
a series of box plots showing the Phred quality score distribution
at each base position for the
Each box plot shows the median Phred score, the 25th and 75th percentiles,
and the most extreme scores that are not considered outliers. An outlier
is defined as a point that is more than 1.5 times the interquartile
distance from the median.
Handle to axes object containing generated plot.