Improved error reporting when loading satellite and perspective camera models

Until now, Digi3D.NET did not take into account the extension of the project files from which the orientations of the satellite or conical camera models were extracted, so that if for example we renamed a .PRJ file from Inpho to .TXT extension and loaded it, the program loaded it correctly. This is because the program tried to load the file with all available extensions (Inpho Summit Evolution, LPS, etc.), and if one of them managed to load the file correctly, it was considered valid. In case of failure, as it had been tested with all supported extensions, the error message that was given was a generic message, which gave no hint to the user, being difficult to locate the error. As of today the program does take into account the file extension, so if the satellite model orientations are stored in .PRJ format of Inpho, the file extension must be .PRJ. Thanks to this, the program can now display error messages specific to a particular extension. You can see this new functionality in the following video: