Easier definition of the axial driver and a ScalarDriver

[LemurPwned]

If we want to set a constant value for an Axial driver we need to do something like:

AxialDriver(ScalarDriver.getConstantDriver(H[0]),
            ScalarDriver.getConstantDriver(H[1]),
            ScalarDriver.getConstantDriver(H[2])))

instead, perhaps an easier way:

AxialDriver(*H)

Scalar Driver can also be assumed to be constant by default:

ScalarDriver(val) == ScalarDriver.getConstantDriver(val)