draw_mp_distance_distribution does not accept sampling a number of
sequences again. It is better to use head before to reduce sequence
number
test adapted to changes in draw_mp_distance_distribution
remove_outliers to outlier_threshols. Somo pep8 fixes
Merge branch 'master' of ssh://pb:2203/seq_crumbs
update some functr to use outlier_threshold
remove unused imports a global variables
draw boxplot implemented
minor fixes in boxplot draw
minor bug bix in calculate dist range
bugfixes: RuntimeErrors where fixed when there was not data
bugfix: continue when getting None instead of a intcounter
change mapping function apis
update bowtie2filter to new mapping api
remove creation of index in bowtie2filter
fix test plot to use new draw_histograms api
use pysam as an optional module
adapt trim function to new mapping api
update filter_chimeras to new mapping api
refactoring draw_distance_distribution
add test data