added sol script to 1.3

exercises/ex01/solutions/beale_grad.mod

+reset;
+
+var x := 4.0, >= -5, <= 5;
+var y := 0.4, >= -5, <= 5;
+
+subject to
+f1: (x*(1.0-y)-1.5)*(1-y) + (x*(1.0-y^2)-2.25)*(1.0-y^2) + (x*(1.0-y^3)-2.625)*(1.0-y^3) = 0;
+f2: - (x*(1.0-y)-1.5)*x - (x*(1.0-y^2)-2.25)*2*x*y - (x*(1.0-y^3)-2.625)*3*x*y^2 = 0;
+
+#option solver conopt;
+#option solver knitro;
+#option solver loqo;
+#option solver minos;
+#option solver snopt;
+#option solver ipopt;
+#option solver baron;
+#option solver couenne;
+
+solve;
+
+display x, y;