NativeJ 1.0.x project files

The project file extension in NativeJ 1.0 is .prj. In NativeJ 2.0 and above, the project file extension is changed to .njp, and file association capabilities are implemented so that you can launch a project file by double-clicking on it.

Despite the change in extension, the project file format remains the same. Hence you can simply rename the extension of old .prj files to .njp, and launch them in NativeJ 2.0 and above.