Add a test to check VtR is deterministic

Given the (*exact*) same input, VtR should produce the same (bit identical) output.

It would be good to add a test which checks this behaviour to make sure no change causes a regression.

Input includes;
 * Code revision
 * Command line arguments
 * Compile options
 * Input files
 * Random seed

It is not expected that things are identical if any of these change.