Custom Breadcrumbs Views should not default to menu breadcrumbs

As Custom Breadcrumb Views runs in a hook_views_pre_render() it gets called for any View on a page and only sets the breadcrumbs if there are accompanying settings.
However, if the current View does not have any settings then it defaults to custom_breadcrumbs_set_menu_breadcrumb(). This means that any previous breadcrumbs (such as those set by custom breadcrumbs node configuration) are wiped out in favour of building breadcrumbs from the menu.

If Custom Breadcrumb Views does not want to make changes, it should simply do nothing so that other modules settings are not wiped out (as hook_views_pre_render() is called quite late in the build process it will often be the last implementation called).

Note: custom_breadcrumbs_set_menu_breadcrumb() is called in custom_breadcrumbs_init() on every page so the default behaviour is still to build from menu when applicable.