Implement OneTimeSetUpAttribute and OneTimeTearDownAttribute; deprecate TestFixtureSetUp and TestFixtureTearDown; modify SetUpFixture and TearDownFixture to use new one time attributes
Modify SetUp/TearDown so that teardown is only run for one level if setup ran previously at the same level
Modify OneTimeSetUp/OneTimeTearDown so that teardown is skipped if corresponding setup is never run
Add comment explaining algorithm for identifying setup and teardown methods
Merge pull request #109 from nunit/setup-and-teardown

Setup and teardown changes for NUnit 3.0