new banding code for tmap

gistfile1.c

 if(end + 1 < sams->n) {
          if(sams->sams[end].strand == sams->sams[end+1].strand //same strand
             && sams->sams[end].seqid == sams->sams[end+1].seqid) {
              sam_start = sams->sams[end].pos;
              sam_end = sams->sams[end].pos + sams->sams[end].target_len;
              sam_next_start = sams->sams[end+1].pos;
              sam_next_end = sam_next_start + sams->sams[end+1].target_len;
              if ( (sam_next_end > sam_end) && ((sam_next_end - sam_end) <= opt->max_seed_band) ) {
                  end++;
                  keep_banding = 1;
              } else if ( sam_next_end <= sam_end ) {
                  end++;
                  keep_banding = 1;
              } else {
                  keep_banding = 0;
              } 
              if (keep_banding) {
                  continue; //look for more banding opportunities
              }
              
              
          }
            
      }