Allow internal URLs in the custom paths

Problem/Motivation

We need to use internal Drupal paths like node/1 in the "Paths to replace with custom breadcrumbs" textarea as target URLs.

Using aliases in not convenient, as changing an alias makes us to update the custom path respectively.

Also, when on a multi-lingual sites the aliased path might contain language and country prefixes, and using regexp in every line to cover those prefixes is cumbersome. The internal paths do not contain those prefixes, and thus we can cover all the languages/countries easily.

Proposed resolution

Check custom path against internal path in addition to checking it agains an aliased URL.