QtCreator stores a file containing amongst other things the path to where
your build tree is and what parameters you used for the configuration
process. These data is user-specific and should not be stored in version
control.
If you open the project in QtCreator again after having made changes
to CMakeLists.txt outside of it, it may create a new user file which
should be ignored just like the original.
find_package only searches for FindXxx-modules in the path specified by
CMAKE_MODULE_PATH; other paths are supposed to contain config-mode
modules (much like pkgconfig).
Generate the config-mode module in the installation directory using the
same template as is used for the one in the build directory, only
selectively swapping some directories in the relevant variables.
Client programs/libraries that uses CMake as their build system should
be able to point at the directory of a OPM-core build tree and have its
library picked up from there.
