use indexing syntax to extract variables from JuMP.model

Orb_AutFN.jl

@@ -113,7 +113,7 @@ function constrLHS(m::JuMP.Model, data::OrbitData, t)
 end
 
 function addconstraints!(m::JuMP.Model, data::OrbitData, l::Int=length(data.cnstr); var::Symbol = :λ)
-    λ = getvariable(m, var)
+    λ = m[var]
     for t in 1:l
         d, d² = data.laplacian[t], data.laplacianSq[t]
         lhs = constrLHS(m, data, t)
@@ -153,7 +153,7 @@ end
 
 function λandP(m::JuMP.Model, data::OrbitData)
    info(PropertyT.logger, "Solving SDP problem...")
-   varλ = JuMP.getvariable(m, :λ)
+   varλ = m[:λ]
    varP = data.Ps
    λ, P = PropertyT.λandP(data.name, m, varλ, varP)