Merge pull request #28 from hultqvist/master

Adding public MailboxAddress parser.
Expanded on previous pull request and documented the API additions
Fixed InternetAddress Parse/TryParse semantics to be consistent with the BCL
Improved documentation.
More doc updates.
Don't forget to add a newline at the end of the Sender: header

Fixes issue #29
When encoding an address list, don't forget to separate addresses with a ','

Fixes issue #30
Updated xml docs
Added remarks to various MimeEntity methods and properties.
Added MimeKit*Lite* csproj/sln files which do not include the cryptography support

Fixes issue #25
Added new convenience method to Header to override the charset when getting the value

Addreses issue #31 in the best way I can think of
Bumped version to 0.20.0.0
Add Link for RFC7103

RFC7103: Advice for Safe Handling of Malformed Messages
Merge pull request #32 from vdaron/patch-1

Add Link for RFC7103
Use the cryptographic RNG instead of Random() for generating boundaries

Using Random() could potentially produce identical boundary strings
due to its use of the system clock as the seed value and that causes
mail clients like Thunderbird to break (they can't handle nested
multiparts that use identical boundary strings).
Don't include <> around the Message-Id or Content-Id property values.

This makes it easier to construct HTML mail having it reference images/etc
via the Content-Id (string.Format ("cid:{0}", part.ContentId)).
Modified IContentObject to provide an "Open()" method to get access to the decoded stream

This replaces the Stream property which uselessly provided the raw encoded stream.
minor code cleanup
Fixed UnitTests after change to Message-Id/Content-Id semantics
Fixed MimePart to recognize Content-Transfer-Encoding: uuencode