CMake Build Configuration Updates, master branch (2020.03.12.)
While reviewing atlas/atlasexternals!618 (merged) I found that this code is not nearly in a state that I would really like.
I spent a bit of time to:
- Bring the CMake configuration to the same style that GeoModelCore and GeoModelIO use;
- Teach the CMake build how to build XercesC and nlohmann_json by itself, if the user asks for that;
- Created a GitLab CI configuration for building the code in a few different ways, to test these improvements.