Add binned scoring option

[joshfactorial]

There is an earlier attempt, but we ran into issues, so this will need to be revisited.

[joshfactorial]

Closing — binned quality scoring was implemented and merged in PR #304 (commit 1be27ed, "Implement binned quality scoring for Illumina instruments (#293)").

Available on develop/main:

• neat/quality_score_modeling/presets.py — named instrument presets
• --quality-preset flag and explicit -Q bin list, wired into model-seq-err and model-qual-score
• Documented in the README ("Binned quality scoring for modern Illumina instruments").