Temperature divided by distance should be either invalid, or should have the unit of "°F/m", but not "°F lightyears"

[yurivict]

This produces bogus units:

> (100 °C to °F) / 1 lightyear
212 °F lightyears

Here is another bogus result:

> 1 meter / 1 lightyear
9460730472580800 meters^2

[printfn]

This relates to #76, you can work around it by adding parentheses: (100 °C to °F) / (1 lightyear)

[printfn]

closing as duplicate of #76