added ModelingToolkit as a dependency

Author: adediego

Project.toml

@@ -14,6 +14,7 @@ IterativeSolvers = "42fd0dbc-a981-5370-80f2-aaf504508153"
 JuAFEM = "30d91d44-8115-11e8-1d28-c19a5ac16de8"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 LinearMaps = "7a12625a-238d-50fd-b39a-03d52299707e"
+ModelingToolkit = "961ee093-0014-501f-94e3-6117800e7a78"
 NearestNeighbors = "b8a86587-4115-5ab1-83bc-aa920d37bbce"
 OrdinaryDiffEq = "1dea7af3-3e70-54e6-95c3-0bf5283fa5ed"
 ProgressMeter = "92933f4c-e287-5a05-a399-4b506db050ca"
@@ -22,7 +23,6 @@ SharedArrays = "1a1011a3-84de-559e-8e89-a11a2f7dc383"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
-SymEngine = "123dc426-2d89-5057-bbad-38513e3affd8"
 Tensors = "48a634ad-e948-5137-8d70-aa71f2a747f4"
 VoronoiDelaunay = "72f80fcb-8c52-57d9-aff0-40c1a3526986"
 
@@ -35,12 +35,12 @@ GeometricalPredicates = "0.3, 0.4"
 Interpolations = "0.11, 0.12"
 IterativeSolvers = "0.7, 0.8"
 LinearMaps = "2"
+ModelingToolkit  = "3.0.1"
 NearestNeighbors = "0.4.4"
 OrdinaryDiffEq = "5.18"
 ProgressMeter = "1"
 RecipesBase = "0.7, 0.8, 1.0"
 StaticArrays = "0.10, 0.11, 0.12"
-SymEngine = "0.6, 0.7, 0.8"
 Tensors = "1.0.1"
 VoronoiDelaunay = "0.4"
 julia = "1"