Fix headings with colspans. If the heading contains a colspan, we still
need to include information in the header line about the colspecs.
Fix headerless tables. The top line should encode colspan information.
Closes#10855.
This handles row and colspans. Partially addresses #6344.
It also ensures that cells won't wrap text in places where it
wouldn't normally wrap, even if this means making the cells wider
than requested by the colspec. (Closes#9001. Closes 7641.)
Parameters are different, so this is a breaking [API change].
Markdown, RST, and Muse writers have been adjusted to
use the new `gridTable`.
Previously we used our own homespun formatting. But this
produces over-long lines that aren't ideal for diffs in tests.
Easier to use something off-the-shelf and standard.
Closes#7580.
Performance is slower by about a factor of 10, but this isn't
really a problem because native isn't suitable as a serialization
format. (For serialization you should use json, because the reader
is so much faster than native.)
John MacFarlane