This is an implementation of an idea we discussed a while ago; a launcher for town-specific
commands.

The idea is to put town commands in one of three places:

- /town/launcher/core
- /town/launcher/contrib
- /town/launcher/admin

and pair each command with a corresponding .yml file.

For example, the `aup` command is a simple wrapper around elinks that opens our code of conduct. I
put the executable `aup` in /town/launcher/core and matched it with /town/launcher/aup.yml. The
purpose of the yaml file is to provide documentation for your executable, so `aup.yml` looks like:

```yaml
shortDesc: View the town's Acceptable Use Policy
longDesc: |
  This command will open our code of conduct, a type of document that evokes the Acceptable Use
  Policies that governed servers like this in the past. It will open the elinks browser to a
  page on the wiki.
examples: |
  $ town aup           # open the aup
  $ town aup --rainbow # open the aup with rainbow colors
maintainer: vilmibm
```

 and using the launcher is like:

     $ town aup
     $ town aup --rainbow
     $ town writo
     $ town admin ban vilmibm

You can see all the commands with `town help` as well as their descriptions; `town help
aup` would show you the docs from `aup.yml`.

I'd love feedback on this approach while I wrap up this implementation. I can put it up on
git.tilde.town if anyone desires to collaborate (and let me know if you want a git.tilde.town
account).

Remaining TODOs:

- [ ] make tab completion available for common shells
- [ ] document / script submitting a tool for inclusion in contrib
- [x] make little wrappers for things like `mail` and `chat`
- [x] fix arg passing
- [x] test with a command that makes use of stdin/stdout
- [x] add all existing commands to the buckets
- [x] add to users' paths