Support Flat Data

[drewknab]

Support nested Section from flat data.

Nested template:

Hello {{name}}
You have just won {{value}} dollars!
{{#in_ca}}
Well, {{taxed_value}} dollars, after taxes.
{{/in_ca}}

Flat Data Example:

{
  "name": "Chris",
  "value": 10000,
  "taxed_value": 10000 - (10000 * 0.4),
  "in_ca": true
}

Produces Example:

Hello Chris
You have just won 10000 dollars!
Well, 6000.0 dollars, after taxes.

  defp process_if(template, val) do
    case val do
      nil -> ""
      false -> ""
      [] -> ""
      [_ | _] -> val
                 |> Stream.map(&(render(template, &1)))
                 |> Enum.join()
      val -> render(template, val) # With the above example, this val is true. Function render tries to access a key on a boolean value and throws an exception.
    end
  end

Proposed code change adds a case for true and that runs data through render instead of val.

Tests added, previous tests still passing.