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.
This allows to specify a table foot by enclosing it with part separator
lines, i.e., row separator lines consisting only of `+` and `=`
characters. E.g.:
+------+-------+
| Item | Price |
+======+=======+
| Eggs | 5£ |
+------+-------+
| Spam | 3£ |
+======+=======+
| Sum | 8£ |
+======+=======+
The last row, containing "Sum" and "8£", is the table foot.
Closes: #8257
ThomasSoeiro