Implemented vectored exception handling so native code can be debugged while the soft debugger runs.
Code provided by Jonathan Chambers:

* https://github.com/Unity-Technologies/mono/commit/e9f9f7170914c5caaff3e95e09f6f58ecced2a10
* https://github.com/Unity-Technologies/mono/commit/4c2e1db60ccb38e792545d595d85b12ff309a919
* https://github.com/Unity-Technologies/mono/commit/bd7e534aa7da49b89787b8c1b40e165a34c0e960
* https://github.com/Unity-Technologies/mono/commit/b885251a83969d243deabc56bb3d1495d4a971dc
Merge branch 'master' of github.com:greenboxdev/mono