-`Prediction.confidence` method to compute the confidence for a prediction like reported in Prodigal's GFF output.
-`Prediction.sequence` method get the nucleotide sequence of a predicted gene ([#4](https://github.com/althonos/pyrodigal/issues/4)).
### Changed
- Replaced internal storage of input sequences to use a byte array instead of a bitmap.
### Fixed
- Extract `Prediction.gc_cont` number directly from the start node instead of the text representation to get full accuracy.
- Prodigal bug causing nodes on the reverse strand to always receive a penalty instead of penalizing only small ORFs ([hyattpd/Prodigal#88](https://github.com/hyattpd/Prodigal/pull/88)).