Backdrop will now discover <theme>.settings.json configuration files in a theme config folder

Backdrop will now discover any theme settings saved in a config folder in a theme in the format of .settings.json.

The settings file should be registered in hook_config_info() placed in a template.php in the theme root directory.

Note that this provides an alternative for how themes save data to the active configuration. The other methods include syncing from the .info file during enabling, or saving the theme's settings form.

This new settings file can be used as an alternative to info file settings such as settings[]=xxx.