feat(volume_rate): Add cubic_meter_per_min and cubic_meter_per_hour as volume rate units

[Uzaaft]

This PR attempts to add cubic_meter_per_min and cubic_meter_per_hour as volume rate units.

[Uzaaft]

Waiting on #405 before marking this as ready for review.a

[iliekturtles]

Thanks for the PR! Changes look pretty good. Two minor changes below.

[Uzaaft]

Thants for the suggestions, implemented those. :)
While I have you here @iliekturtles . I was wondering if you would be open to implement(or open for a contribution) that adds support for standard and normal conditions to the codebase?
https://en.wikipedia.org/wiki/Standard_temperature_and_pressure

[iliekturtles]

Similar to the other PR can you squash the commits and update the commit message. At the same time you can exclude the mass rate changes and just base this on top of iliekturles/master.

I'm definitely open to STP contributions. AmountOfSubstance already has a few STP specific units. Are you thinking about adding more or something different to more generally support STP?

[Uzaaft]

Similar to the other PR can you squash the commits and update the commit message. At the same time you can exclude the mass rate changes and just base this on top of iliekturles/master.

I'm definitely open to STP contributions. AmountOfSubstance already has a few STP specific units. Are you thinking about adding more or something different to more generally support STP?

well, what I ideally would want is to have a general support of STP wherever it could apply, as well as adding methods to convert from/into other units. I'll have to take a look at how AmountOfSubstance does it.

[Uzaaft]

Everything should be ready now.

[iliekturtles]

Thanks for the PR!