Breadcrumbs not always display the correct path

[TheWitness]

Describe the bug

Cacti breadcrumbs have always driven me mad. So, today I did a deep dive, and there is a bit of code that is not fully rationalized. The logic that was in place may have had a purpose at one time or another, but that purpose has long been diminished. So, a mild re-write was due. This bug is to record that re-write. In this change, we abandon the navigation cache, and simply construct the breadcrumb from the $navigation array that is passed for ever page including well written plugin pages.

Expected behavior

Cacti code should be easier to understand.