This MR in conjuntion with inkscape!5669 allow pass actions xml data to extensons
This MR allow send the path of a XML to the extension when run something like this in command line:
./inkscape --actions="log-start;select-by-id:rect1;query-x;query-y;query-width;log-end;org.mycoolextension" .test.svg
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<logfiledata>
<cout><![CDATA[77.3619]]></cout>
<cout><![CDATA[289.502]]></cout>
<cout><![CDATA[277.333]]></cout>
</logfiledata>
can be cout or cerr for errors and warnings
Is needed by this inkscape MR: inkscape!5669