these changes only apply to very old versions of Doxygen (v1.8.x):
- the searchbar image is not squashed anymore
- background image artifacts in the searchbar are removed

for more details, see
#68

On large screens, the toc is now anchored to the top right of the screen.
A JS-Extension for highlighting the current read progress is provided.
On small screens, the toc is hidden and can be opened by the user.

- update toc CSS to anchor it to the top right
- fall back to inline toc in box on smaller screens (<1000px)
- add install instructions for extension
- updated browser test information
- updated doxygen version recommendation

A CSS rule that is supposed to invert the grahpical class hierarchy in
dark mode was accidently also inverting images in ordinary tables.
This is now fixed.

fixes #72

when no toc is available on the current page, an error would be thrown.
This is now fixed. When no toc is available the code in question is not  executed.

Also removed some unecessary JQuery

Doxygen comes with a special syntax for creating complex tables
(https://www.doxygen.nl/manual/tables.html).
Tables created with the doxygen syntax are now styled the same like
markdown tables.

Additionally, fieldtables have been overhauled slightly and their glow
behaviour has been altered.

- improve styling of default color variable values
- fix some comment typos

I am not sure why this was introduced in the first place. It makes
problems right now and I hope removing it will not break sth else.

The "inherited from" sections in a class documentation are hidden by
default. A small arrow icon indicates that the user can interact with
the given text and expand the items that are hidden behind it.

The icon is an image by default, which comes with two downsides:
1. It's not a vector graphic and looks oldschool on hdpi monitors
2. It cannot be matched exactly to the theme colors

This is why it was replaced by a CSS triangle that comes with a nice
open/close animation as a small bonus! 😊

- fix image color inversion in dark mode for doxygen 1.9.3
- make it more explicit what files are required in sidebar-only
  mode

- directory tables now have an improved spacing
- even row highlights in directory tables have rounded corners
- class list icons (N = Namespace, C = Class, ...) do now scale together
  with the page font size (improved customizability)

the new arrow icon rotates on open/close and is a vector graphic

- update the arrow icon to open the interactive TOC
- minor style improvements & fixes

    - support .PageDoc content class
    - increase title font size to 225%
    - fill gap in section separation lines
    - make param table follow table-line-height variable

When setting SOURCE_BROWSER = YES in the Doxyfile, links to the code
lines where a certain interface is defined are referenced.
When the link is clicked the related sourcecode is shown and the referenced
line is highlighted. The style of the highlight has been improved.

The new Doxygen version comes with some small CSS adjustments
that required fixes in this theme.

Nervertheless it is NOT recommended to update to the new Doxygen
version! Doxygen 1.9.5 comes with scrollbar customizations that don't
work well together with this theme and they can not be
reverted/patched with just CSS.

See doxygen/doxygen#9549

- template parameters can wrap to the next line when they get too long
- return types can wrap on small screens when they get too long
- additional spacing was added to the member declarations table
- add support for class template parameters

fixes #84