Double-check units on the "covariance is too big" warning

[dmcdougall]

[briadam]

The conditional logic for this warning

queso/src/stats/src/TransformedScaledCovMatrixTKGroup.C

Lines 330 to 343 in 469911a

	if (covMatrix(i, i) >= max_val - min_val) {
	// User is trying to specify a uniform proposal distribution, which
	// is unsupported. Throw an error for now.
	std::cerr << "Proposal variance element "
	<< i
	<< " is "
	<< covMatrix(i, i)
	<< " but domain is of size "
	<< max_val - min_val
	<< std::endl;
	std::cerr << "QUESO does not support uniform-like proposal "
	<< "distributions. Try making the proposal variance smaller"
	<< std::endl;
	}

is comparing units of variance (covariance diagonal) to domain bounds. Should probably instead by comparing sqrt(var) to the bounds.