massFlux and parentSI seem incompatible

[maier-m]

massFlux has a parentSI of kilogramsPerSecond
A more appropriate massFlux SI would be kilogramsPerSquareMeterPerSecond
kilogramsPerSecond would be more appropriately massRate

[mobb]

agreed (flux has area in the denominator).
also applies to amountOfSubstanceWeightFlux, which might be a mass-specific rate (?)

other instances of the term "flux" to note:

1. massflux unitType is named arealMassDensityRate, which is fine as is.

2. magneticFlux and magneticFluxDensity include area - sometimes in the numerator, sometimes denominator. Perhaps this is because of unit reductions? Knowing nothing about magnetism, I am not qualified to edit these.

[mobb]

Also note, this one is actually is a mass "flux", but is called a rate.

simplest solution is to rename the unitTypes, and confirm the children match:

massFlux
<unitType id="arealMassDensityRate" name="arealMassDensityRate"> <!--kilogramsPerMeterSquaredPerSecond--> <dimension name="mass"/> <dimension name="length" power="-2"/> <dimension name="time" power="-1"/> </unitType>

amountOfSubstanceWeightRate
<unitType id="amountOfSubstanceWeightFlux" name="amountOfSubstanceWeightFlux"> <!--molesPerKilogramPerSecond--> <dimension name="amount"/> <dimension name="mass" power="-1"/> <dimension name="time" power="-1"/> </unitType>

massRate:
<unitType id="massFlux" name="massFlux"> <!--kilogramsPerSecond--> <dimension name="mass"/> <dimension name="time" power="-1"/> </unitType

[mobb]

related to #285

[mobb]

1. massFlux is now massRate
2. arealMassDensityRate is now massFlux
3. amountOfSubstanceWeightFlux is now amountOfSubstanceWeightRate