Use ARGV0 to invoke other binaries inside AppImage

packaging/AppImage/AppRun

@@ -17,4 +17,9 @@ export OPENSSL_CONF="$scriptdir/openssl.cnf"
 # unset `QT_STYLE_OVERRIDE` as a precaution
 unset QT_STYLE_OVERRIDE
 
-$scriptdir/UltiMaker-Cura "$@"
+BIN=`basename "$ARGV0" .AppImage`
+if [ -f $scriptdir/$BIN ]; then
+    $scriptdir/$BIN "$@"
+else
+    $scriptdir/UltiMaker-Cura "$@"
+fi;