* nonguix/build-system/binary.scm (lower): Adapt the default value of the
install plan.
* nonguix/build/binary-build-system.scm (new-install): New procedure.
(old-install): Rename former `install' procedure to this.
(install): New procedure that dispatches over old-install and new-install.
* nonguix/build-system/binary.scm: New file.
* nonguix/build/binary-build-system.scm: New file.
* nonguix/build/utils.scm: New file.
* nonguix/utils.scm: New file.