Fix build and update NuGet packages.
Merge branch 'PostSharp3'
Merge remote-tracking branch 'origin/master'
Update PostSharp OSS license to PostSharp 3.
Add support for calling DontEnforceSetupVerification() after .Throws or .SetupGet.

Closes Issue #12.
Merge remote-tracking branch 'origin/master'
Add support for calling DontEnforceSetupVerification() after .SetupGet().Callback.
Fix remaining Moq wrapped calls which were yet unwrapped (related to issue #15 and issue #21).
Code cleanup.
Fix ISetup<>.Callback() method implementation to return a wrapped version (issue #21).
Fix ISetup<>.Throws() method implementation to return a wrapped version (issue #21).
Merge branch 'master' into PostSharp3