BudanTables.jl

I think question 1 falls into Optionnal dependencies and allow options for packages.

I end up using Polynomials.jl to represent polynomials and, via Requires.jl, the user can choose between Polynomials.roots and PolynoamialRoots.roots. It is also possible not to use Polynomials.jl but some redundant code will be loaded anyways.