fix phpdoc
[mms] Add Horde_ListHeaders#listHeadersExist().
[mms] Added Horde_Mail_Rfc822_List#first() function.
Move these headers strings to constants
Fix smartmobile popup position

Signed-off-by: Michael M Slusarz <slusarz@horde.org>
This is a bit clearer to visually parse
Fix mailto url

Signed-off-by: Michael M Slusarz <slusarz@horde.org>