HTML: Make the nav bar in Doxygen act more like the nav bar in Sphinx

[wmamills]

The Nav bar in Doxygen has a lot of bells and whistles but to me ends up being less useful than the one in Sphinx.

This current state is as inherited from Doxygen & doxygen-awesome-css.
It may be that this activity does not who up when all pages of a given "site" are from doxygen.
In doxygen-awesome-css he displays a per page TOC on the right side so the lack of auto-expand of the current page is not so bad.

The current state (after PR #26 ) is as follows:

Doxygen:

• Expand and collapse each section on any page
• Remember that state from page to page

Sphinx:

• Each page shows its expanded children, its siblings (collapsed) and parents, grandparents etc.
• All other top level items are collapsed
• The highlight is always on the page you are looking at

Example: (all items refer to Nav Bar on the left of the page)

• Start at the top level Sphinx
• Click libmetal
• Click Modules
• Expand Modules by clicking the tiny arrow on the left when you hover over Modules
• Click IO Interfaces
• Expand IO Interfaces
• Expand DMA Interfaces
• Click on the Logo to take you to the top level Sphinx
• Click on libmetal

The page content will show the libmetal start page but the Nav bar will show the expanded IO Interfaces.

What should happen:

We should be able to fix this with Javascript. On entry to any page of the Doxygen content, collapse other topics and expand the current one. We can still let people expand and collapse on a given page but I think most people will not even notice the arrows that appear when you hover.

Extra credit give each level of Nav bar a unique style so the highlight can match what Sphinx does.
(But the Sphinx level highlights should be more subtle than currently is the case.)