Polynomials.@variable clashes with JuMP.@variable

The introduction of the convenience macro @variable a few months ago was somewhat inconvenient for me since it clashes with the same macro in JuMP, resulting in `WARNING: both Polynomials and JuMP export "@variable"; uses of it in module Main must be qualified`. So now either I `import Polynomials` and prefix every method with `Polynomials.whatever()`, or I have to import everything I need explicitly. Admittedly this is not a huge inconvenience, but @variable wasn't a game-changing addition for Polynomials either and might in retrospect have been better named differently.

Namespace clashes with the giants of the Julia ecosystem need to be carefully considered, and JuMP is certainly one of those. At this point though renaming it would be a breaking change, so please revisit this issue if you need to change the API surface of Polynomials some time in the future.