Full Mailer class support

[splitbrain]

The current plugin does not support all the features of the Mailer class. This means HTML mails and attachments do not work. SwiftMail should be capable of this, the problem is that it uses its own mechanisms for these features.

I see two possible ways to support them:

1. only use the SMTP transport and auth classes of SwiftMail and do no longer rely on the rest of the framework
2. find a way to inherit from Mailer and reimplement it's methods by remapping them to SwiftMail components

I slightly prefer the first method, but am not sure how simple this would be. I don't see that I'll have the time to do this in the foreseeable future (unless someone hires me), so a pull request that implements this would be very welcome.

[ktp1976]

Alternative:
https://github.com/PHPMailer/PHPMailer
Used it in my projects and it works flawless with or without html

[ktp1976]

As easy as:

        $mailer = new PHPMailer();
        $mailer->SetLanguage('de','components/phpmailer/language/');
        $mailer->Mailer   = "smtp";
        //$mailer->SMTPAuth = true
        //$mailer->Username = $this->App->cfg['mail']['auth']['name'];
        //$mailer->Password = $this->App->cfg['mail']['auth']['pass'];
        $mailer->Host     = 'smtp.server.address';
        $mailer->Port     = '25';
        $mailer->From     = 'sender@where-ever.com';    
        $mailer->FromName = 'Mail sender name';
        $mailer->WordWrap = 120;
        $mailer->Subject  = 'My subject';
        $mailer->IsHTML($message != strip_tags($message));
        $mailer->CharSet  = 'UTF-8';
        $mailer->Body  =  $message;
        $mailer->AddAddress('abc@xyz.com);
        $mailer->AddAddress('xyz@abc.com);
        $mailer->Send();

[splitbrain]

HTML Mails are now supported in the SMTP plugin.