Fixes #13. Adds option to ignore bases from 5' and 3' ends of reads, with a different number of bases ignored for read_1 and read_2 in paired-end data.
Fixes #13. Adds option to ignore bases from 5' and 3' ends of reads, with a different number of bases ignored for read_1 and read_2 in paired-end data.

PeteHaitch/methtuple,PeteHaitch/methtuple,PeteHaitch/methtuple