Truncate frequencies used in calibration

For calibration, the log10(frequnecy_array) causes log warning messaged (due to taking the log of 0). To resolve this, and also to provide a slight speed up, this only calculates the values in the frequency mask

bilby/gw/calibration.py

@@ -100,7 +100,7 @@ class CubicSpline(Recalibrate):
         Parameters
         ----------
         frequency_array: array-like
-            The log-frequency values to calculate the calibration factor for.
+            The frequency values to calculate the calibration factor for.
         prefix: str
             Prefix for calibration parameter names
         params : dict
@@ -117,7 +117,7 @@ class CubicSpline(Recalibrate):
                                 for ii in range(self.n_points)]
         delta_amplitude = interp1d(
             self.log_spline_points, amplitude_parameters, kind='cubic',
-            bounds_error=False, fill_value=0)(frequency_array)
+            bounds_error=False, fill_value=0)(np.log10(frequency_array))
 
         phase_parameters = [
             self.params['phase_{}'.format(ii)] for ii in range(self.n_points)]