Implement breadcrumbs

[serra]

This is a new issue, instead of #58. Work on that issue was discontinued.
I merged the work from #58 onto this branch;

Todo:

• Merge and test work from Implementation of breadcrumbs #58
• Unit test and review the "parent concept" in navigation routes
• Merge in the changes from the "navigation overhaul" Navigation Overhaul #68

[MisterJames]

Let me know if you need anything from me on this for the #68 merge, I'd be happy to help.

[serra]

For #58 the an explicit parent route property was introduced, this parent is used to recursively build the breadcrumbs. This is closely related to the navigation routes. ATM it's not really clear to me what the proposed changes to the navigation routes are, and how that will affect this issue.

I figured it would be best to wait and see how #68 works out and then merge that work in.

You could try and see if there are any objections to the explicit parent and how it is set. If it's in the line of the expected overhaul, I can proceed with this issue immediately.