Handled EmailReference

This pull request handles the EmailReference pointer message which has been described in #4.
Yes, it does.  I just made a working prototype in Qaiain.

##### Manual testing

I discovered a [nice feature](http://msdn.microsoft.com/en-us/library/ms164241.aspx) that allows you to configure a local directory for a Simple Mail Transport Protocol (SMTP) server and have the *.eml (e-mail message) file saved locally on disk.

Here is how to configure Qaiain to save all sent e-mail messages locally:

```xml
<system.net>
  <mailSettings>
    <smtp deliveryMethod="SpecifiedPickupDirectory">
      <specifiedPickupDirectory pickupDirectoryLocation="c:\Users\Nikos\Desktop\"/>
    </smtp>
  </mailSettings>
</system.net>
```

Then, you can use a tool called [EML Reader](http://www.emlreader.com/)<sup>*</sup> to open the saved e-mail from disk.

##### Results

The original file's bytes and the attachment's files bytes are identical.

|   |Size   |Size on disk   |
|---|---|---|
|Original file (.mp3)  |15.8 MB (16,584,380 bytes)   |15.8 MB (16,584,704 bytes)   |
|Attachment (after save as...)   |15.8 MB (16,584,380 bytes)   |15.8 MB (16,584,704 bytes)   |

##### Notes

Theoretically, it works even with > 20 MB files (although the SMTP servers will probably block it).

I uploaded the prototype code I used to test this in a [temporary gist](https://gist.github.com/moodmosaic/74d5439fb75b78054840).

-----

<sup>*</sup>EML Reader is new to me. I always run executable files that I don't know through [Sandboxie](http://www.sandboxie.com/).