Shortens Facets Pretty Paths aliases.

• Removes the term ids from the term aliases. If a machine name is not available yet, there is a fallback to the default term coder, with the term id, to guarantee unicity.
• Multiple values (Facet items) are delimited by a dot, the Facet alias is present only once.

So we have e.g.: /color/black.yellow.red
instead of /color/black-1/color/yellow-2/color/red-3