Merge pull request DirectoryTree#41 from DirectoryTree/fix-stream-tra…

…nsport-key

Use correct `ssl` stream transport options key for `tls`

Merge pull request DirectoryTree#39 from DirectoryTree/bug-35

Bug 35 - Mbox Reader should handle handle message splitting more reliably

Merge pull request DirectoryTree#33 from DirectoryTree/attachment-con…

…tent-id

Add ability to retrieve attachment Content-ID (cid)

Merge pull request DirectoryTree#32 from DirectoryTree/mbox-reader

Add `.mbox` file reader

Merge pull request DirectoryTree#29 from DirectoryTree/bug-28

Give `Attachment` blank content stream when empty from server

Merge pull request DirectoryTree#27 from DirectoryTree/bug-26

Allow attachment filenames to be nullable

Move comment from interface

Move comment from interface

Merge pull request DirectoryTree#24 from DirectoryTree/message-interface

Unify common message methods in `MessageInterface`

Merge branch 'file-message'