The CMake var CMAKE_ARGS was removed on the second CMake run.
As CMake runs always twice at least this removed the help info.
I changed implementation to simply cache the variable and set it
on the first CMake run only.

- enabled version suffixes such as -rc1
- git hash is omitted when on a tag

RPATH is now executable_path/../lib only.

See disabled-tests.log

Speeds up CMake run significantly and reduces Conan output a lot.

Currently set on envinf56 and envinf11w to 3 threads with
1 OpenMP thread each.

The timeout is maximum runtime for one benchmark. Was 15 minutes before.

BUILD_TESTING is a CMake convention used widely.

https://cmake.org/cmake/help/v3.9/module/FeatureSummary.html