+ - tweak the short options. I think dump files should be a
+ second-class feature in general, so that --dump and --load should
+ be represented by capital options. That leaves -d free to be
+ --depth, which I think is more generally useful.
+ * while I'm tweaking the options list, "[all modes]" ought to
+ say "[most modes]", due to --scan-dump.
+
+ - New mode: --remove, to destroy the data file. Handy for
+ totally self-contained usage: "-s . -w -R".
+