ACTSFW-27 add cmake build options
This adds build options to activate various optional components that are deactivate by default. This includes a refactorization of the cmake configuration.
- Build options and configuration are now always explicit, i.e. if you request to build w/ Geant4 via
USE_GEANT4=on
Geant4 becomes a requirement. At no point are components build depending on the available software. It is always the other way round: you define what you want and CMake makes sure that all the required software is available. - Searching for software via
find_package(...)
is done centrally in the mainCMakeLists.txt
file instead of multiple times in every subdirectory. - Optional components are activated by wrapping the
add_subdirectory
call in an smallif() ...
block instead of wrapping the full content of theCMakeLists.txt
file in multiple ifs.
Fixes ACTSFW-27 and is required to get !45 (merged) working.