Add Unit Tests

[martindevans]

Investigate adding unit testing to the project. Possibly with the NoSoundNotRealtime or WavWriterNotRealtime outputs modes set.

[martindevans]

Added a unit test project with a single test which creates a system - this confirms that loading the DLLs works in a test project and we can at least write unit tests.

[HakanL]

Very good to have a structure for writing unit tests! 👍