Make the tests run again

The `check` target was broken because of `dist_TESTS`; it _must_ be just
`TESTS`, not distributed.

Use `dist_check_SCRIPTS` instead so that they can be packaged as scripts
for checking the system.
On bad args, show usage and exit

The lsrc(1), mkrc(1), rcup(1), and rcdn(1) commands will now print a
usage message and exit immediately (with 64, `EX_USAGE`) when given an
option it does not understand.

This includes `--version` and `--help`.

Normal `-h` will print usage and exit successfully, as normal.

Closes #59.