Cell width is excluding padding/margins

[DylanDeWolff]

Currently if the user would like to have a table that spreads the width evenly over four columns you have to specify the width of each cell manually. However, padding/margins only get added during table processing. This means the user has to take into account these additions beforehand otherwise the combined column width ends up larger than the width of the table (which will result in content being removed or the specified width being ignored in order to make the table fit). It would be nicer if the width was considered all inclusive.