* CRM/Memberdashboard/Page/Benefits.php (CRM_Memberdashboard_Page_Benefits)
[hasValidMembership]: New method.
[postProcess]: Restrict POST actions to members only.
[run]: Pass 'hasValidMembership' variable to smarty template.
* templates/CRM/Memberdashboard/Page/Benefits.tpl: Display an access
denied page if the user is a non-member.