[ulaform] handle arrays in mailto.php

[Chuck Hagenbuch]

Quoting Bo Daley <bo at tilda.com.au>:

> this patch allows the mailto driver to handle values supplied in an array
> structure (like fields of type 'Multiple Selection' or 'Set'). Previously
> data in these fields was appearing in the generated emails as 'Array'.

Committed, thanks!

-chuck

--
Charles Hagenbuch, <chuck at horde.org>
Born right the first time.