Prevent setting custom cell widths and allow setting default column ratios

Hello,

I was wondering if anyone was working on updating the plugin to allow dynamic changing of the default row layout (line 869 in js/siteorigin-panels.js) as well as a default column ratio. That would be very beneficial to have.

Another request is for the ability to disable custom cell width changing, as in the draggable bar to resize and the editable number box in the center of the cell. We need to lock down the editors to specific layouts, so that would be nice too.

I have also made a modification that would nice to have in the plugin, it allows you to do an add_filter to set the default number of columns when creating a new row.
Replace line 288 in tpl/js-templates.php with the following:

$cells = apply_filters('siteorigin_panels_column_cells', 2 );
$cells_field = '<input type="number" min="1" max="8" name="cells"  class="so-row-field" value="'.$cells.'" />';