Improve group/module bar layout in Doxygen pages

[jhlegarreta]

Description

When a class belongs to numerous modules/groups, the group/module links become a little bit cluttered, e.g.

The layout should be improved for better understanding the module/group membership of a given class.

Expected information

Group and module names should be better separated/organized in the group/module bar.

Actual information

Group and module names become cluttered; one does not really know which one is a module/group.

Versions

master

Additional Information

Slightly related to #3656.

[jhlegarreta]

Slightly related to this. It might be worthwhile to add a "More..." link at the top of the classes that links with the "Detailed description" section of each class, otherwise it is not apparent where the description is.

e.g. in VTK:

[albert-github]

Small side note:
In C++ there is nowadays also the term module (introduced in doxygen in version 1.9.8), to overcome confusion between a doxygen group which was called "module" and the C++ term doxygen groups are nowadays called "Topics" in the documentation.

Maybe something for ITK to think about as well.