validateDoubleArrayMeta/ fitToDoubleStepSize function numeric not robust for small step size.

[Johann Krauter]

The following doubleArray ito::Param failes in the validateDoubleArrayMeta function for the value 0.5 which is in within the range min - max. 0.6 passes than the validation.

ito::float64 widths[8] = {
        0.00000000200,
        0.00000000200};
    paramVal = ito::Param(
        "doubleArray",
        ito::ParamBase::DoubleArray | ito::ParamBase::In,
        2,
        widths,
        new ito::DoubleArrayMeta(
            0.00000000200, 999.99999999975, 0.00000000025, 1, 2, 1),
        tr("")
            .toLatin1()
            .data());
    m_params.insert(paramVal.getName(), paramVal);

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