Adds a [pmproseries] shortcode to display a specific series post list.

pmproseries_shortcode.php

function pmproseries_shortcode($atts) {
    global $post;
    extract(shortcode_atts(array(
        'id' => $post->ID
    ), $atts));

    //start output buffering
    ob_start();
    $series = new PMProSeries($id);
    $series->getPostList(true); //true echoes post list
    $temp_content = ob_get_contents();
    ob_end_clean();

    return $temp_content;
}
add_shortcode('pmproseries', 'pmproseries_shortcode');