Cmake package config helpers

[boxanm]

1. Update Cmake version
2. Use CMakePackageConfigHelpers to generate CMake config and version files
3. Fill libnabo_INCLUDE_DIRS and libnabo_LIBRARIES variables

[simonpierredeschenes]

Good job! There is only one minor comment to address. Also, I was wondering, did you test to make sure it is still possible to refer to the libnabo target in a modern cmake way in dependent projects (e.g., target_link_libraries(my_executable libnabo::nabo))?

[boxanm]

Good job! There is only one minor comment to address. Also, I was wondering, did you test to make sure it is still possible to refer to the libnabo target in a modern cmake way in dependent projects (e.g., target_link_libraries(my_executable libnabo::nabo))?

The libnabo_LIBRARIES variable is just a placeholder for libnabo::nabo , so nothing prevents you from using that instead. Although I personally think it's cleaner not to hardcode the namespace and library name and to use the variable instead.