handle masked array in separation_array in gnc.Ncdata.break_by_region
1. add from_dataframe_error in Pdata.Pdata to build pdata with errors.
2. change the bleftshit in bar plot.
add Ncdata_dict_to_dataframe_panel
add cm_contrast_red2blue and imshow
small change in bmapcontourf
the labelaxes object for Pdata