Add `docker-run-env` tool

- sets all ENV vars from a `.env` or `config/application.yml` file
Add `headlessly` tool

- wraps the Ruby `headless` gem
- tries to unbundle, if necessary
Add `pg1` utility

- fires up a standalone PostgreSQL server
- basically obsolete now that `docker run postgres:9.3` is easy
Add `split-cert` utility for splitting PEM files

From example.com.crt, containing a server certificate and the signing CA
and intermediate certs, it will generate:

- `example.com.combined.crt` = the original file
- `example.com.authorities.crt` = everything but the server's cert
- `example.com.standalone.crt` = just the server cert
Add X11 src files to default target
Add `x-xpdf-active` utility

- `x-xpdf-active NAME` checks to see whether an `xpdf` instance is
  running with that remote name
Add `toggle-pulse-zeroconf` utility

- unloads and reloads the PulseAudio Zeroconf (Avahi) module
- tries to move sinks back to a good state
Fix namedirs initialization in `alias-directory`

- sets to default if not already set
- tries to create the default if needed
- TODO: figure out why `load-namedirs` isn't scoping $namedirs properly
Set Vim filetype when editing Zsh dotfiles

- autoload/function files don't (usually) have extensions
Add `$only` option to `run-tests`

E.g., to only run `tsp` and `cuke -r`:

```sh
only='tsp cuke' in-btrfs-snapshot with-fresh-test-db run-tests
```