When the `float` class is attached to a table, a standard
floating `table` will be generated instead of a `longtable`.
Placement can be specified via the `latex-placement` attribute.
This will help, especially, those who use two-column layouts,
since `longtable` is incompatible with these.
Small change to the default LaTeX template: the `caption`
package is included and a default spacing set between the caption
and the table.
Closes#1023.
John MacFarlane