The page that came out black, and the one that came out blank

[tannevaled]

render v0.11.0 and reader v0.6.0 between them fix two things a person using
this application would have seen, and one they would not have known to look
for.

the black page a four-component JPEG written by an Adobe tool stores its
ink inverted, and Go's image/jpeg does not turn it back, so
the page came out almost solid black. 35 of 8 300 corpus
files carry one. Turning it over alone breaks eleven DVLA
forms, which carry /Decode [1 0 1 0 1 0 1 0] and were drawn
correctly only because that was ignored too; both halves
are fixed together.

the blank page reader v0.6.0 stopped a damaged stream coming back with a
nil error, which made a strict decode return nothing where
it used to return the fragment. render v0.11.0 reads every
stream through the salvaging API, so plots/P12positive01.pdf
goes 188 770 inked pixels -> 0 -> 188 770 across the three
states.

the noise 273 image masks in the real forms carry an encoded filter,
and their compressed bytes were being painted as a stencil.
236 are faxes, now decoded; the 9 that remain are JBIG2 and
are not drawn rather than drawn wrong.

Against poppler, page by page and with both given the same box, this
application's renderer now agrees on 1 633 of 1 633 real forms and 2 223 of
2 223 arXiv files, with a median of 0.19% and 0.08% of pixels differing.