* Ignore path constructors that do not begin with m
Per PDF Reference Section 4.4.1, "path construction operators may be
invoked in any sequence, but the first one invoked must be m or re to
begin a new subpath." Since pdfminer.six already converts all `re`
(rectangle) operators to their equivelent `mlllh` representation, paths
ingested by `.paint_path(...)` that do not begin with the `m` operator
are invalid.
In addition to the advantage of hewing to the PDF Reference, this change
also avoids the `ValueError: not enough values to unpack (expected 2,
got 1)` error raised by the ` pts = [apply_matrix_pt(self.ctm, pt) for
pt in raw_pts]` line in `converter.py` when parsing PDFs that
(erroneously) include `("h",)` paths.
* Update CHANGELOG.md
Co-authored-by: Pieter Marsman <pietermarsman@gmail.com>