Make tables snap to the grid

[dyve]

Table columns should be able to snap to the grid. Ideally like this:

<tr class="row">
    <td class="span2 columns">
        ....
    </td>
    ....
</tr>

There will probably be some colspan issues, but I'd not pay too much attention to that (leave something for user IQ).

[dashed]

This is something I'd be interested in.

[mdo]

Solved in the dev branch. Had to get a bit more specific with quite a few rules, but as an interim this works I think.