New build system

Hi all, David Cournapeau's Bento build system (a replacement for distutils) is maturing nicely. I'd like to switch to it eventually, but for now I've simply put all the necessary changes in the 'bento' branch. Bento is entirely self-contained, so just check out the branch and do: make bento It keeps track of changes to C files, so incremental builds work. Commands are provided for generating the docs, running tests, etc. Let me know what you think. Regards Stéfan