Gallery column width calculation needs more granularity

[akozak]

In line 712 of wp-includes/media.php where the column width is calculated for the gallery css snippet:

$columns = intval($columns);
        $itemwidth = $columns > 0 ? floor(100/$columns) : 100;

        $selector = "gallery-{$instance}";

        $output = apply_filters('gallery_style', "
                <style type='text/css'>
                        #{$selector} {
                                margin: auto;
                        }
                        #{$selector} .gallery-item {
                                float: left;
                                margin-top: 10px;
                                text-align: center;
                                width: {$itemwidth}%;                   }

itemwidth should be calculated as

$itemwidth = $columns > 0 ? round(100/$columns,1) : 100;

This gives the width better precision. I've read that IE ignores the decimal, but it works on at least Firefox, so there is no reason not to let it have a decimal value. You could even increase the number of decimal points.

Everything more than two decimal points gets cut to two.

Should work well on Mozilla, and not make any difference on Opera and IE. However, t needs heavy testing.

The patch still had floor() instead of round(). Attached an updated patch, but also, is this really needed?