Source Plugins
--------------

The ``source`` and ``dest`` use a second plugin system used to load and save
configuration data.  The provided plugins are:

**id**
  The specifier is a string value that points to a specific config
  item id within the active config storage.

**file**
  The specifier is a ``*.yml`` file along with optional path. If no path
  is given, the config/templates directory of the current module is used.

Normally the source plugin type is determined from the string specifier itself.
For example, if the string ends in ``.yml`` then the ``file`` plugin is used.

To override the source plugin type, use the ``*_type`` option (``source_type`` or
``dest_type``) with the name of the plugin.

The source can also be a raw array of configuration data. This data is passed
to the plugin system in case a complex plugin needs to parse the additional
data.  But since the ``id`` and ``file`` plugins both expect a string value, any
array value is currently passed through as raw data.