Cleaned up `CMakeLists.txt` files in subdirectories so that the minimum reqiured
version is set only at the beginning of the top-level `CMakeLists.txt` file

Riccardo Maria Bianchi authored 1 year ago and Vakhtang Tsulaia committed 1 year ago

Introduce new I/O helpers, new I/O tests, and a 'loglevel' to steer the verbosity; and remove old cmake options