Add flags :)

`--env` for specifying the environment (if not set, it falls back to `EZ_ENV`, then falls back to 'dev')

`--debug` for enabling Symfony Debug (if not set, it falls back to `EZ_DEBUG`, then falls back to `env == 'dev'`).

`--help`, `--config` and `--version` from PsySH.

Adds support for psysh-style includes as well. Any arguments passed after the flags will be included into the REPL — like when you run `php foo.php`, but it drops you into PsySH after including them :)