Fix #7387, operations between ranges and non-real numbers

[simonster]

This seems pretty trivial, but it occurs to me that it would be nice to have generic fallbacks for these functions for all AbstractArrays so that it's not necessary to reimplement them for user-defined types. In that case we would presumably want to use similar instead of comprehensions, but then there's the problem of getting the element type right, which is ultimately related to how we decide to handle #7258. So for now, I'm punting on that and just making the minimal change to fix this issue.

[kmsquire]

I'm wondering if it would be reasonable to construct a new range instead of an array... Thoughts?

[simonster]

There are already more specific methods that construct a new range for +/-/* with a real, so these methods would only be called for !(Number <: Real). At present we couldn't actually construct ranges involving complex numbers, since StepRange needs <, which is not defined for Complex, and FloatRange is restricted to reals. There are also other issues with expanding ranges to non-reals: the colon operator is only well-defined for complex if angle(step) == angle(stop-start), and I don't know enough abstract algebra to say what should happen for other number types.