* Made dazl responsive to the `DAML_LEDGER_URL` environment variable so that if a URL is not specified in code, it is read from the environment instead.
* Factored out some typical dazl boilerplate into a new API, `dazl.run`.
* Changes to how dazl is configured. This breaks backwards compatibility in the `dazl.client.config` module, so if you are referring to any of those classes directly, there may be minor code changes required (this is not common).