properly support `--help` and `--version` command-line flags by using `getopt_long()`

[cooljeanius]

lsbom needs to support --help and --version before we can move to gnits strictness with automake; this will require a move to getopt_long()

[cooljeanius]

7cab59d kinda fixed this; it added support for --help and --version and moved to gnits strictness with automake, but it did so kinda hackishly, and I still want to move to getopt_long() eventually, so I'm keeping this bug open for that.