These changes reflect the suggestions by Attila Krasznahorkay on CMake
installation setup.

For additional details, see: !31 (comment 3976398)

This new install confuration works fine on macOS + CMake 3.19.1
Source: https://cmake.org/pipermail/cmake/2019-September/070014.html

This reverts merge request !29

These are meant to simplify the build configuration of sub-projects
that make use of GeoModelCore.