Have one Makefile, instead of recursive
Remove useless lib folder
Remove useless obj folder
Remove recursive Makefiles
Minor change
Make unit-tests and simplify into one makefile
Move Doxyfile to doc folder
Add comments to the Makefile
Merge branch 'simplify_makefile'
Edit python scripts to remove FutureWarning.

* Check numpy arrays with "is None" instead of "== None".