Recursive DBSCAN (#84)

* 🎨📝🐎 Update docstrings
* Update median completeness calculation to not incorporate all contigs but rather just cluster values.
* 🎨 Change RecursiveDBSCANError exception to BinningError
* 🐛 Update metabin import in user.py from mag.py
* 🎨🔥 Remove default 'z' column in run_dbscan function.
* 🎨 add_metrics func now returns 2-tuple with cluster_metrics dataframe for median completeness lookup.
* 🎨 Change default domain marker count lookup in add_metrics to raise error if domain does not match.

* 🎨🐎 Add naive HDBSCAN implementation as clustering method.
📝 Add comments for break conditions within get_clusters function.

* 🎨📝🐎 hdbscan implementation now scans across min_samples and min_cluster_size.