And similar for `\midrule` and `\bottomrule`.
This facilitates redefining `\toprule`, `\midrule`, and `\bottomrule`
without needing to gobble the ()s.
Closes#8223.
The writer uses features from the longtable package to define the table
foot. Furthermore, the table's bottom rule is now part of the foot,
where it previously was given as part of the body.
These commands take optional arguments with () and [],
which can lead to problems if the content of the table
cell begins with these characters.
Closes#8001.
In some cases, the rounding performed by the LaTeX table
writer would introduce visible overrun outside the text
area.
This adds two more decimal places to the width values.
John MacFarlane