At this point, it is an interface to the cache. It will be extended
to be a universal interface for access to and manipulation of
configuration-time data (defintions, properties on targets,
directories, source files etc).
This will allow porting all command implementations away
from the cmMakefile and cmTarget classes, and result in something
more-purely related to configuration-time processing of cmake
commands. That should serve at least the following goals:
* Split the CMake implementation more definitively into three
stages: Configuration, computation and generation, and be able to
implement each optimally for memory access patterns etc.
* Make better IDE integration possible by making more configuration
data available.
* Make it possiblte to use a smaller library than CMakeLib.a in
cpack and ctest, resulting in smaller executables.
* Make it possible to run the configure step multiple times in
the same CMake run (#14539).
Manage its lifetime in the cmake class, and add a convenience accessor
to cmMakefile.
Stephen Kelly