[FIX] Adapted the sam/bam module to new stream modul.

4 POS Int [0,231-1] 1-based leftmost mapping POSition

4. POS: 1-based leftmost mapping POSition of the ﬁrst matching base. The ﬁrst base in a reference sequence has coordinate 1. POS is set as 0 for an unmapped read without coordinate. If POS is 0, no assumptions can be made about RNAME and CIGAR.