todo
----

- (cxx) break down user configuration and generic rules
- (deep) make it work for a sample source tree
- (c) port the build system in cxx to c
- (auto-c) make a c version of auto-cxx
- tools to use skeleton code easily (a la autoproject)
- (C++) support for command line parsing and other common tasks

done
----
* (cxx) Why doesn't ifdefs work in automatic dependency include directives?
  Fix it.

* (cxx) Factor the Makefile into smaller ones, for automatic rules, user defined vars, etc.

