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

it seem that signed integers are actually used:
/*! @typedef
  @abstract Structure for core alignment information.
  @field  tid     chromosome ID, defined by bam_header_t
  @field  pos     0-based leftmost coordinate
  @field  bin     bin calculated by bam_reg2bin()
  @field  qual    mapping quality
  @field  l_qname length of the query name
  @field  flag    bitwise flag
  @field  n_cigar number of CIGAR operations
  @field  l_qseq  length of the query sequence (read)
 */
typedef struct {
	int32_t tid;
	int32_t pos;
	uint32_t bin:16, qual:8, l_qname:8;
	uint32_t flag:16, n_cigar:16;
	int32_t l_qseq;
	int32_t mtid;
	int32_t mpos;
	int32_t isize;
} bam1_core_t;

and in http://samtools.github.io/hts-specs/SAMv1.pdf it says:
l_seq                 Length of SEQ                         int32 t