Closes #10683.

Alert readers to a threat relating to iframe in HTML.
Add LaTeX, Typst to the list of formats that have an `include`.

Closes #10682.

Otherwise we get `**content**` which means strong emphasis.

This is a more robust solution than using `_`, which won't work
for intraword emphasis.

Closes #10642.

They are invalid but do occur in the wild.
Closes #10643.

See #10673.

It should not accept escaped newlines.
See #10672.

Users commonly complain about the warning when producing HTML
documents without an explicit title. It seems that an info message
is more appropriate, since pandoc's default here (using the input's
base name) ensures compliance with the standard and many users
are happy with that default.  Those who want to make sure the
message is seen can use `--verbose`.

Closes #10671.

Closes #10394.

Otherwise we get undesirable results, as the format's native
citation mechanism is used instead of (or in addition to) the
citeproc-generated citations. Closes #10662.

Closes #10661.

Closes #10659.

Closes #10650.

This reverts commit cbe67b96.

Word sets `w:firstColumn="1"` by default for tables.  You have to find
the Table Design tab and explicitly uncheck "First Column" to make this
go away.  In most cases, I don't think writers intend to designate
the first column as a row head, so this commit is going to produce
unexpected results.  In addition, because of the table normalization
done by pandoc-type's `tableWith`, any table containing a colspanned
cell in the left-hand column will get broken if the first column is
designated a row head.  For these reasons it seems best to revert this
change, which was made in response to #9495.

Closes #10627.

with a YAML exception.  See #10231.

This seems to be required for iOS books app to display the space.

Certain `role` and `epub:type` attributes should only be on the section
(and indeed, many `role`s give a validation error if left on the heading
element).

Just a typo for author prefix that was causing authors to have the suffix as
prefix and suffix in the XML.

Closes #10621.

(In the case where there is no subtitle.)

Closes #10619.

See #10610.

Previously we tried to match curly quotes as well as straight
quotes, producing Quoted inlines.  But it seems better just to
assume that those who use curly quotes want them passed through
verbatim.

This also fixes an (unintended) bug whereby curly single left
quotes would sometimes be changed to single right quotes.

Closes #10610.

We used to insert extra spaces to ensure that the content respected
the four-space rule.  That is not really necessary now, since pandoc's
markdown and most markdowns don't follow the four-space rule.

Those who want the old behavior can obtain it by using
`-t markdown+four_space_rule`.

Closes #7172.