small one column layout bug

[Hunter58]

If you use a layout with only a main content block and there are values in the leftcol, rightcol margins (for instance for indenting or centering) the table is malformed.

Entering one margin only a colspan 1 is used for header en footer but there are actualy 2 cells. If both margins are used a colspan 2 is generated but there are three cells. So there is a cellmismatch in the table/rows.

It is not realy a major problem, but I thought I should mention this because on the other layouts (2 and 3 col) the colspan is changed correct