Layout of top of ITK documentation pages

[albert-github]

Currently with the doxygen 1.9.6 version the ITK top of the pages of the documentation look like:

with the doxygen version 1.13.2 this will change in:

The question is what is the preferred layout?

There are 2 points

• the treeview: setting GENERATE_TREEVIEW
• the blue bar at the top: setting DISABLE_INDEX

The defaults for these settings changed from:

GENERATE_TREEVIEW = NO
DISABLE_INDEX = NO

to

GENERATE_TREEVIEW = YES
DISABLE_INDEX = YES

(It doesn't hurt to explicitly set the wanted version already for older versions)

[albert-github]

As e.g blaster changed to doxygen version 1.13.2 the result is that there is a "treeview" and the top blue line is gone, to revert to the old layout, proposed patch: diff.patch

[dzenanz]

Thank you for pointing this out. I like the new layout better. I think it is more functional. Therefore, I am explicitly selecting it in #5220.