Description of proposed changes

• read/plot: support geometry h5 file with other undefined datasets, e.g. "displacement", which is useful for single-pair displacement products for generic sharing purpose.
• read.read_attribute(): ignore Std while grabbing UNIT
• writefile.write(): add optional ds_unit_dict arg to specify different data unit for each dataset, same as layout_hdf5()
• geocode: same h5 compression bwt. input/output

Reminders

• Pass Codacy code review (green)
• Pass Circle CI / local test (green)
• Make sure that your code follows our style. Use the other functions/files as a basis.
• If modifying functionality, describe changes to function behavior and arguments in a comment below the function declaration.
• If adding new functionality, add a detailed description to the documentation and/or an example.