Improved Pix4D support

We have just added to Digi3D.NET the ability to natively load files  _calibrated_external_parameters.txt from Pix4D. Until now to load aerial triangulations from Pix4D we had to copy the file  _calibrated_external_parameters.txt with extension .EO, in addition to editing it to remove the extension of the files in the first column of all lines of this file and in addition to ensuring that the importer's configuration of projection center and rotation orientations adapted to Pix4D (angular units = sexagesimal and rotation order = omega - phi - kappa). Well, from now on it is no longer necessary to perform this task, since Digi3D.NET natively loads these files without making any modifications.