Fix InitialConstantChange (#122)

Author: pkofod

src/initialguess.jl

@@ -148,6 +148,7 @@ function (is::InitialConstantChange{T})(ls, state, phi_0, dphi_0, df) where T
             αguess = one(state.alpha)
         end
     end
+    is.dϕ_0_previous[] = dphi_0
     state.alpha = αguess
 end
 

test/initial.jl

@@ -120,6 +120,10 @@
     is = InitialConstantChange(snap2one=(0.25,1.0))
     is.dϕ_0_previous[] = 0.1*dphi_0
     is(ls, state, phi_0, dphi_0, df)
+    @test is.dϕ_0_previous[] == dphi_0
     @test state.alpha == 1.0
     @test ls.mayterminate[] == false
+    dϕ_0_rand = rand()
+    is(ls, state, phi_0, dϕ_0_rand, df)
+    @test is.dϕ_0_previous[] == dϕ_0_rand
 end