These display helptext and current version of the application,
respectively.

`wrt -h` and `wrt --help` still work, as do a new `wrt --version` and
`wrt -v`.  I think the subcommand forms are useful (and echo a growing
norm for this kind of interface), but the others should be discoverable
for users with traditional expectations.  Both basic help and version
info should be readily available without much thought, which I think
justifies the repetition.