Make menu icon export compatible with Inkscape 1.0

Though usually one would export directly to "${3}", Inkscape 1.0 had
its command line options changed by people who apparently think that
backwards compatibility is some kind of swear word: Whereas earlier
Inkscape versions would export to a file called foo.png.tmp, newer
behaviour is to ignore the user's wishes & write to foo.png.png –
unless one asks it to write to a filename with a .png extension,
Inkscape 1.0 changes the filename extension to .png each time.

As we do not know the extension of "${3}", we have to use the
extension, then rename the resulting file to the proper name;
only that way the export works with Inkscape 1.0 & earlier …

menu/icon.png.do

@@ -7,9 +7,23 @@ SVG_FILE=${2%.png}.svg
 # and width. Low resolutions lead to blurry edges, as Minetest scales
 # menu icons up. High resolutions lead to jagged edges, as Minetest
 # scales menu icons down. Height & width of 72 pixes seem to work.
+#
+# Though usually one would export directly to "${3}", Inkscape 1.0 had
+# its command line options changed by people who apparently think that
+# backwards compatibility is some kind of swear word: Whereas earlier
+# Inkscape versions would export to a file called foo.png.tmp, newer
+# behaviour is to ignore the user's wishes & write to foo.png.png –
+# unless one asks it to write to a filename with a .png extension,
+# Inkscape 1.0 changes the filename extension to .png each time.
+#
+# As we do not know the extension of "${3}", we have to use the
+# extension, then rename the resulting file to the proper name;
+# only that way the export works with Inkscape 1.0 & earlier …
 >&2 inkscape \
 	--file="${SVG_FILE}" \
-	--export-png="${3}" \
+	--export-png="${3}".png \
 	--export-area-page \
 	--export-height 72 \
 	--export-width 72 \
+
+mv "${3}".png "${3}"