Tommaso Pavese

Check for `ecto_sql` instead of just `ecto` in the conditional compilation guards. It might solve https://github.com/tompave/fun_with_flags/issues/137.

Introduce the concept of entry point modules that a host application must implement in order to access the FunWithFlags API. This is adapted from [what Ecto does with its Repo](https://github.com/elixir-ecto/ecto/blob/v3.11.1/lib/ecto/repo.ex#L205)....

Ensure that the loaded config survives an application reload

2

Pass `persistent: true` to `Application.put_env/4`, so that the new config values will survive the application load and reload events. Documented [here](https://hexdocs.pm/elixir/Application.html#put_env/4). As example, it's used by [`Mix.Config.persist/1`](https://github.com/elixir-lang/elixir/blob/v1.4.5/lib/mix/lib/mix/config.ex#L237-L244).