Headers already sent

Hello.

When WP_DEBUG is set to true, there are a lot of PHP warning messages about headers being already sent in Line 25 in visual-portfolio/classes/class-get-portfolio.php.

We’ve changed the IF statement to check if the headers were already sent before calling session_start();.

function vpf_session_start() {
if (( ! is_admin() && ! session_id() ) && !headers_sent()) {
session_start();
}
}

Please check it as well and include the fix in the next release.

Thank you for the great plugin.