Gerbview: added  support forSF  (scale factor), IO (Image Offset), OF (Offset) and MI (Mirror) commands.

Fixed a bug about Aperture Definition having parameters for an aperture macro. See Changlog for not yet supported RX274X commands. Having still problems with arcs in some gereber files.

 Known bug: aperture macros having parameters are incorrect: parameters are not transmited correctly. Work still in progress.