What is the role of the AutoFixture.NUnit.Addin? FWIW, I removed the AutoFixture assembly reference and it compiled successfully..

Also, I noticed that it references the AutoFixture.NUnit assembly only in one place ([here](https://github.com/gertjvr/AutoFixture/blob/nunit/Src/AutoFixture.NUnit.Addin/Builders/AutoTestCaseProvider.cs#L67)).

Is it *really* necessary to introduce, support, and maintain the AutoFixture.NUnit.Addin project in AutoFixture? Wouldn't it be better if this project could be (somehow) part of the NUnit project itself?