Remove DataStructures dependency (#133)

Author: blegat

Project.toml

@@ -4,7 +4,6 @@ repo = "https://github.com/JuliaAlgebra/DynamicPolynomials.jl.git"
 version = "0.4.5"
 
 [deps]
-DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 Future = "9fa8497b-333b-5362-9e8d-4d0656e87820"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 MultivariatePolynomials = "102ac46a-7ee4-5c85-9060-abc95bfdeaa3"
@@ -14,7 +13,6 @@ Reexport = "189a3867-3050-52da-a836-e630ba90ab69"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
-DataStructures = "0.17, 0.18"
 MultivariatePolynomials = "0.4.1"
 MutableArithmetics = "0.3, 1"
 Reexport = "0.2, 1.0"

src/DynamicPolynomials.jl

@@ -4,12 +4,9 @@ import Future # For `copy!`
 
 using Reexport
 @reexport using MultivariatePolynomials
-const MP = MultivariatePolynomials
+import MultivariatePolynomials as MP
 
-import MutableArithmetics
-const MA = MutableArithmetics
-
-using DataStructures
+import MutableArithmetics as MA
 
 include("var.jl")
 #const CommutativeVariable{O,M} = Variable{Commutative{O},M}