Fix navbar fragment and allow parent link

[CravateRouge]

Purpose

Enhancement:

1. with this PR, "menu main" with children can also have a clickable link:

menus:
 main:
  - name: Services
   hasChildren: yes
   url: /services
  - name: Audit
   parent: Services
  url: /services/audit

Fix

1. if "menu main" has no "url" it will default to href='' instead of href='/' (better to do logical testing with a $url="" in templating code)
2. if only fragment provided as url: "#about" it is now associated to home page and not relative page, as intended before but the concatenating was forgot.

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