Convert a ModuleDescription linked list to a Python list (and release the former).

def module_description_list(head):
    """Convert a ModuleDescription linked list to a Python list (and release the former).
    """
    r = []
    if head:
        item = head
        while item:
            item = item.contents
            r.append((item.name, item.shortname, item.longname, item.help))
            item = item.next
        libvlc_module_description_list_release(head)
    return r