Fixes bare (GFM) autolink positions. cmark reports a bare URL's start wrong in two ways and its end right in both, so both are now handled by measuring back from the end.
Wrong by the length of the preceding lines. The start is reported as an offset into the paragraph's content buffer, not a column on its line. On a single-line paragraph the two coincide to within one character — which is why the +1 adjustment in 1.4.0 looked correct. After a soft line break the error grows by every byte of the preceding lines, so a https://one.example.com on line 2 reported column 12 instead of 3. Consumers highlighting from position painted only a suffix of each URL and left the front as plain text.
Missing entirely. A URL that opens a paragraph is reported at column 0, so position(in:) — all-or-nothing by design, since every node type uses it — mapped neither end and the link had no usable range at all. This was the known gap listed in the 1.4.0 notes; bare autolinks are now adjusted before that check, and the end is mapped from its own line and column when needed.
The start is derived by walking back the length of the URL as written in the source. That matters: GFM expands www.example.com to http://www.example.com, so measuring the destination would walk back too far.
The two text nodes around the link were wrong for the same reason and are repaired with it — the autolink's own child takes the link's whole position, and the run in front of it stops where the link starts. Where the URL opens the line, cmark emits a leading text node with an empty literal whose span cannot be clamped without inverting it; that one is left as it is, since it carries no text.
No API change. 130 tests, 1 skipped. (#11)