Support for QSEQ parsing.

This relates to issue #389.  @audy, @wasade.

Added parse_qseq, QseqIterator, support in the factory for .qseq and .qseq.gz.  Added unit tests.

For Sequence ID, I am using: "machine_name"_"run_number":"lane_number":"tile_number":"x":"y"#"index"/"read".  Example: CRESSIA_242:1:2204:1453:1918#0/1.  Do you agree?

I set qual_id to seq_id.  Do you agree?


This suggests that `ascii_to_phred64` and `ascii_to_phred33` be placed outside of `.fastq`. @jairideout, can you comment about this from source organization perspective? I know there is quite a bit of shuffling going on for the 0.2