add gls files to make clean

Makefile

@@ -16,4 +16,9 @@ images/wide.jpg: images
 	convert -size 100x60 xc:skyblue -fill white -stroke black  -draw "ellipse 50,30 40,20 45,270" images/wide.jpg
 all: docs test
 clean:
-	rm -rf *pdf *.aux *.toc *.acn *.acr *.log *.ptc *.out *.idx *.ist *.alg *.glo svg-inkscape
+	rm -rf *pdf *.aux *.toc *.acn *.acr *.log *.ptc *.out *.idx *.ist *.alg *.glo \
+	*.slo \
+	*.sls \
+	*.glg \
+	*.gls \
+	svg-inkscape