Pandoc used to emit a `header` class on the `tr` element that forms the table header. This is no longer needed, because `head > tr` will do the same thing.
Similarly, pandoc used to emit `even` and `odd` classes on `tr`s, allowing striped styling. This is no longer needed, because one can use e.g. `tbody tr:nth-child(2n)`.
We now omit these classes, which have a good chance of conflicting with classes used for other things.
Closes#9325.
* Markdown writer now includes a blank line at the end
of the row in a single-row multiline table, to prevent it from being
interpreted as a simple table. Closes#4578.
* Markdown reader does a better job computing the relative width of
the last column in a multiline table, so we can round-trip tables
without constantly shrinking the last column.
ThomasSoeiro