fastq file compression by pbzip2

Since April 2017, DRA has been compressed fastq files by pbzip2 instead of bzip2. The fastq files mean all DDBJ/EBI/NCBI SRA fastq files.

The pbzip2 compresses/de-compressed with multiple threads, it processed files much faster than bzip2 if CPU resources allow. Extension of all fastq files is '.bz2' and indistinguishable. Because pbzip2 and bzip2 are compatible, so if you de-compress our fastq.bz2 files by pbzip2, you may have faster speed for pbzip2-compressed one and normal speed for bzip2-compressed one.