The following table feature are now supported in ConTeXt:
- colspans,
- rowspans,
- multiple bodies,
- row headers, and
- multi-row table head and foot.
The wrapping `placetable` environment is also given a `reference` option
with the table identifier, enabling referencing of the table from within
the document.
* 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.
