ShapedCoil fix: Multiply control response by turns

The toroidal current is `coil.current * coil.turns`
but the `turns` variable was not used in the calculation
of the flux or field components.

This change should bring `ShapedCoil` in line with other coils
in their behaviour.

freegs/shaped_coil.py

@@ -93,12 +93,13 @@ def __init__(self, shape, current=0.0, turns=1, control=True, npoints=6):
 
     def controlPsi(self, R, Z):
         """
-        Calculate poloidal flux at (R,Z) due to a unit current
+        Calculate poloidal flux at (R,Z) due to a unit current in the circuit
         """
         result = 0.0
         for R_fil, Z_fil, weight in self._points:
             result += Greens(R_fil, Z_fil, R, Z) * weight
-        return result
+        # Multiply by turns so that toroidal current is current * turns
+        return result * self.turns
 
     def controlBr(self, R, Z):
         """
@@ -107,7 +108,7 @@ def controlBr(self, R, Z):
         result = 0.0
         for R_fil, Z_fil, weight in self._points:
             result += GreensBr(R_fil, Z_fil, R, Z) * weight
-        return result
+        return result * self.turns
 
     def controlBz(self, R, Z):
         """
@@ -116,7 +117,7 @@ def controlBz(self, R, Z):
         result = 0.0
         for R_fil, Z_fil, weight in self._points:
             result += GreensBz(R_fil, Z_fil, R, Z) * weight
-        return result
+        return result * self.turns
 
     def inShape(self,polygon):
         Shaped_Coil = Polygon([shape for shape in self.shape])