Add support for non-integer types with ToQuantity

[AdamDawes]

I'm writing an application that displays numbers in the form "1 hour", "2 hours", etc. and so using the ToQuantity method looked perfect. However the number of hours in this case is not a whole number, as the application supports half-hours too. This means I can't use ToQuantity as it only supports int or long as parameter types.

Could we have additional overloads to support decimal, double etc. parameter types for this method?

[niallermoran]

I have created a simple solution for this that accepts doubles and decimals, but only supports ShowQuantityAs.Numeric, e.g. 0.2 hour will return 0.2 hours.

If this works I can submit a PR