Fix Doxygen warnings

In latests release few Doxygen warnings slipped - CI was broken as the time regarding them due to a Gitlab bug that has now been resolved after Gitlab server upgrade.

Locally on macOS I didn't get them at the time; I saw them now but I gather it is due to the fact Doxygen was upgraded recently.

Anyhow, this ticket solves the warnings - one of them by extending the exclusion in the script that analyses Doxygen output.