New version 2.0 with added functionality, refactoring, and PEP8 compliance.
 Preferred entry point is now create_error_map(), which handles opening files, selecting optimal regions to perform the autocorrelation, and applying the calculated weight scale factor to the supplied weight map. Supports saving the output error map in inverse variance (ivm), variance (var), or rms/sigma (rms) formats via the map_type parameter.