Automatically get Slicer executable path.
If SLICER_EXECUTABLE environment variable is not set then the slicerio.server will attempt to start
the application at the path specified in winreg.HKEY_CLASSES_ROOT, "Slicer\shell\open\command
Automatically get Slicer executable path.
If SLICER_EXECUTABLE environment variable is not set then the slicerio.server will attempt to start
the application at the path specified in winreg.HKEY_CLASSES_ROOT, "Slicer\shell\open\command