Tables with colspan

[davidfarmer]

When a knowl opens in a table, it makes a new row (tr) that contains
one cell (td). That td is given a colspan attribute so that
it goes the full width of the table.

To figure out the colspan, it counts how many td are in the row
containing the knowl link. But what if that row contains td's
that have a colspan? Answer: it will undercount the td's, and the
knowl will not take up the full width of the table.

Test case:
http://spot.pcc.edu/~ajordan/MTH95Fall2018/section-calendar.html