* Move all unit tests to Engine/Tests
* Fix Margin.EdgeSubtract
* Fix Capsule.Contains
* EnvironmentVariables.Remove if it's null
* Fixed ray trace never returning startedsolid
* Fix HistoryList.Navigate on empty list
* Fix GameObject.WorldPosition accepting NaNs
* Fix flex: initial expanding to the wrong grow/shrink
* Translation.TryConvert shouldn't throw on invalid enum strings
* Skip sound file tests on machines with no audio device
