Correct units in DL1ab output, when processing v0.9 files

v0.9 and v0.10 DL1 files differ in that the latter have units for some of the columns, which are missing in the former. With this change we ensure that the DL1 parameters table has consistent units for all DL1ab outputs, regardless of whether the input file was v0.9 or v0.10

lstchain/scripts/lstchain_dl1ab.py

@@ -459,7 +459,10 @@ def main():
                 dl1_container['sin_az_tel'] = np.sin(params['az_tel'][ii])
 
                 for p in parameters_to_update:
-                    params[ii][p] = u.Quantity(dl1_container[p]).value
+                    if np.isscalar(dl1_container[p]):
+                        params[ii][p] = dl1_container[p]
+                    else:
+                        params[ii][p] = dl1_container[p].value
 
                 images[ii] = image
 
@@ -472,6 +475,11 @@ def main():
                 write_table(image_table, outfile, dl1_images_lstcam_key, overwrite=True, filters=HDF5_ZSTD_FILTERS)
 
             add_config_metadata(params, config)
+            # Make sure we have the right units in all columns which have them
+            # (this is needed to process DL1 files produced with v0.9!):
+            for p in params.columns:
+                params[p].unit = dl1_container.fields[p].unit
+
             write_table(params, outfile, dl1_params_lstcam_key, overwrite=True, filters=HDF5_ZSTD_FILTERS)
 
             # write a cat-B calibrations in DL1b