Port Makefile+setup scripts from shell+make to Python (maybe waf?)

[mithro]

We are increasingly getting more stuff in python through make.py, load.py and mkimage.py. These duplicate a lot of logic in the Makefiles. The bash scripts in ./scripts/ are also getting quite large and not portable to windows.

Writing Make and Bash is sucky. Writing Python is better.

Maybe we should replace all of that with something like waf?