Comment 2 for bug 1662531

Attached is a pair of Python extensions, which will appear on the Extensions->Export menu. The extension "Pre-Process File Save As..." will perform the operations:
- save a copy of the file in a temporary location
- open a new instance of Inkscape and load the new file
- perform "Edit->Select All" and "Path->Object to Path"
- load the "File->Save As..." dialog to allow saving as .plt, .hpgl, or .dxf
- close the new file silently and return to the original file, which is unchanged.