v0.3.3

Changes

• Some internal refactoring with the aim to always correctly handle mixed calls
  to next(), read_record_set() and seek().
• Added len() and is_empty() methods to fasta::RecordSet and fastq::RecordSet
• Added from_path_with_capacity() to the FASTA and FASTQ readers
• Thanks to changes in buf_redux 1.0.1
  (version now enforced in Cargo.toml), LTO is not necessarily required for full performance any more.

Bug fixes

• Fix issue where calling read_record_set() after next() lead to incorrect
  reading (#20)