Temporary copy out of the MonoMac assemblies - so that I can build without using the MonoMac file copy and registry hacks

Try to reduce some of the `public angst` by changing the `Obsolete` into a `\\\` comment - but still want to encourage people to move to the newer code if we can...

Add Mac to VS sln (see http://tofutim.blogspot.com/2013/11/adding-monomac-and-xammac-to-visual.html on adding MonoMac to VS), updated Mac projects to 4.5, updated compile location

refactor attachment interface to take in a stream instead of byte[].  Added a CanSendMail method (useful for osx, not sure for other platform).  Ensure all platform now comply the interfaces (they all throw notimplexception for the ComposeEmail with attachments).