Support for Win64 exception handling.
- unified exception code, no more win32ExceptFilter2 - using win32ExceptFilter(GetExceptionInformation()) instead
- displaying stack frames for Win64 build using appCaptureStackTrace/appDumpStackTrace (there's no frame pointers in VS/x64 builds)
- added "target" command line option for build.sh
- added "--64" option for test.sh