New option to set sidebar/main content breakpoint

[Jonnyauk]

Currently you have to add something like this to make the main content/sidebar collapse to full width at a breakpoint:

function my_wfx_layout_responsive( $input ){
    return $input . ' mq-small-min-box-1-1';
}
add_filter( 'wflux_sidebar_1_with_content_1', 'my_wfx_layout_responsive' );
add_filter( 'wflux_content_1_with_sidebar_1', 'my_wfx_layout_responsive' );

Wonderflux needs a new admin option to set this - maybe as simple as selecting breakpoint definition as new option - but may need to consider multiple sidebars?!