Ancient versions of CMake required else(), endif(), and similar block
termination commands to have arguments matching the command starting the block.
This is no longer the preferred style.
by tweaking the filename and adding 2 categories:
Troubleshooting and Advanced
* use the EXCLUDE_SYMBOLS to clean the class list
(insteaded of a homemade bash script)
* remove the broken "exemple list"
* re-structure the unsupported directory as mentionned in the ML and
integrate the doc as follow:
- snippets of the unsupported directory are directly imported from the
main snippets/CMakefile.txt (no need to duplicate code)
- add a top level "Unsupported modules" group
- unsupported modules have to defined their own sub group and nest it
using \ingroup Unsupported_modules
- then a pair of //@{ //@} will put everything in the submodule
- this is just a proposal !
