remove obsolete comment

nifty/operators/fft_operator/fft_operator.py

@@ -147,12 +147,6 @@ class FFTOperator(LinearOperator):
         self._backward_transformation = TransformationCache.create(
             backward_class, self.target[0], self.domain[0], module=module)
 
-        #MR FIXME: these defaults do not work for SHTs as they are currently
-        #   implemented. Should have either float or complex on both sides.
-        #   It would be great if this could be harmonized in some way.
-        #   The simplest (and maybe safest, but expensive) solution would be
-        #   to allow only complex-valued fields on both sides of an FFT between
-        #   RGSpaces.
         # Store the dtype information
         if domain_dtype is None:
             self.logger.info("Setting domain_dtype to np.complex.")