Initial nunit lite commit
f
First attempt at a MonoMac based test runner.

When nunitlite-4.5.csproj is compiled we now produce a MacUnit.exe
file. This can be used to run test suites which contain MonoMac
based tests. The tests are all run on the main thread and we can
use the 'async' keyword in the tests to give the ability to have
unit tests which yield to the main loop.