* stepmake/stepmake/install-targets.make (local-uninstall): idem.

* stepmake/stepmake/install-targets.make (local-uninstall): idem.

* stepmake/stepmake/install-out-targets.make (local-install-outfiles): idem.

* stepmake/stepmake/help2man-targets.make (install-help2man): idem.

* stepmake/stepmake/generic-vars.make (Module): idem.

* stepmake/stepmake/executable-targets.make (default): use it.

* stepmake/bin/install.py (create_dir): new file. Replace install-sh.

* lily/main.cc (setup_paths): don't inspect $PATH for argv0 with
slashes.
(prepend_env_path): more verbosity.