Wrong stitching when binning_z and phase retrieval are activated

When using simultaneously phase retrieval and binning_z in multi-stage reconstruction, the stitching is not done properly.

Quick tests suggest that the solution would be to (1) multiply the (vertical) phase margin with binning (although we already have options["phase"]["delta_beta"] /= (binning[0] * binning[1]) in ProcessConfig) and (2) use the following in LocalReconstruction:

                curr_z_min += n_slices - margin_down*binning_z
                curr_z_max += n_slices - margin_down*binning_z