Resolve cython and numpy dependencies on setup step

I have a custom Python package on my project where some functionality implemented on Cython. We use it to speed up some of the slowest parts of our code - the syntax is pretty close (it can be identical except some imports) to regular Python. Cython compiled to .so libraries and it has support for fast access to NumPy arrays. The problem - Cython and numpy packages need to be installed before...