Update styles.css

added support for required field (HTML5)
added border:none; for logos and delete deprecated border="0" html attribute
Update html.php

added required attribute to allowed list for input fields
Update login.html

deleted deprecated border="0" Attribute and use css instead
Update header.html

deleted old border="0" attribute and use css instead
Update rcmail_output_html.php

added required Attribute to Login fields
Update mail.html

deleted deprecated frameborder Attribute and use css instead
wrong closing DIV tag
Update addressbook.html

deleted deprecated frameborder attribute and use css instead
Update settings.html

deleted deprecated frameborder attribute and use css instead
Update func.inc

added missing ID for label
Update mail.html

added old frameborder Attribute for IE7 and IE8
Update addressbook.html

added old frameborder Attribute for IE7 and IE8
Update settings.html

added old frameborder Attribute for IE7 and IE8
Update SMTP.php

remove sensless version_compare(). Min PHP Version is 5.2.1 so is a check of PHP 5.1.0 sensless. So never occurs.
Update Socket.php

remove sensless version_compare(). Min PHP Version is 5.2.1 so is a check of PHP 5.1.0 sensless. So never occurs.
Update rcube_imap_generic.php

remove sensless version_compare(). Min PHP Version is 5.2.1 so is a check of PHP 5.1.0 sensless. So never occurs.
Update SMTP.php
Update Socket.php
- Fix detecting Turkish language in ISO-8859-9 encoding (#1489252)
- Fix rewrite rule in .htaccess (#1489240)
Validate all text attachments not only text/plain. This fixes invalid
warning message for a case when pdf attachment is defined as text/html.
See #1489267.