Load a MTZ file as two map objects (fofc, 2fofc) or if amplitudes and phases column names are given, as one map object.
load_mtz filename [, prefix [, amplitudes, phases [, weights [, reso_low [, reso_high ]]]]]
filename = str: filename
prefix = str: object name or prefix {default: filename without extension}
amplitudes = str: amplitudes column name, guess if blank {default: }
phases = str: phases column name, required if amplitudes are given {default: }
weights = str: weights column name, optional {default: None}
reso_low = float: minimum resolution {default: 0, read from file}
reso_high = float: maximum resolution {default: 0, read from file}