make it possible to run a full "re-configure" of the projects without a full rebuild
At the moment we have
-
make configure
to run CMake without wiping the CMake cache -
make purge
to ditch everything and restart from scratch
Sometimes (often, actually) it is useful to force a reconfigure from a clean CMake cache but keep the build artifacts so that they do not need to be rebuilt. For example this might be the case when updating the files generated by lb-project-init
(see #70).