AlignmentHeader.from_dict() silently discards the TP attribute from SQ lines #1237
Description
The TP attribute in sequence lines in the SAM header is used to encode whether a reference sequence is linear or circular. Unfortunately AlignmentHeader.from_dict() silently removes this tag from the data:
> header = { "SQ": [{"SN": "some-plasmid", "LN": 5000, "TP": "circular"}] }
> AlignmentHeader.from_dict(header).to_dict()
OrderedDict([('SQ', [{'SN': 'some-plasmid', 'LN': 5000}])])