Tag

Added
- An index class for efficient in-memory access of sequence features.
- Module for mRNA handling, with a function for selecting the primary mRNA from
a gene or other feature.
- New CLI command `tag pmrna`.
- A new `Score` class for internal handling of feature scores. Not yet included
in the API, and may not ever be.

Changed
- Modules focused on classes / data structure now support more concise imports
(for example, `from tag import Feature` and `tag.Feature` now supported and
preferred over `from tag.feature import feature` and `tag.feature.Feature`).

Fixed
- Resolved a bug with the GFF3Writer failing to print `FASTA` directives
before writing sequences to output.

Changed
- CLI implemented using `entry_points` instead of a dedicated script.

Fixed
- Entry type inference now correct by inheriting from `object`.

Added
- Basic data structures
- Range
- Comment
- Directive
- Sequence
- Feature
- Annotation I/O
- GFF3Reader
- GFF3Writer
- Composable generator functions for streaming annotation processing
- A command line interface through the `tag` script
- Package scaffolding
- README
- documentation
- license
- changelog
- various config files