Clean up temp directory

This has been disabled during early debugging phase and apparently I
just forgot to re-enable it.

Morale: don't use `:` to disable stuff; use `#` (ideally at column 0),
which stands out much more.

src/bin/sfembed

@@ -105,7 +105,7 @@ do_embed() {
     pushd "$tmp" >/dev/null
         mkbody; es=$?
     popd >/dev/null
-    : rm -r "$tmp"
+    rm -r "$tmp"
     return $es
 }