0.4.1

Fixes

• Fix the interface of make_I (#62) (@engintoklu)
• Fix generate_batch returning None (#63) (@engintoklu)
• Fix C decomposition rate calculation on CUDA devices (#64) (@NaturalGradient)

Docs

• Add contribution guidelines (#70) (@engintoklu, @Higgcz)
• Add "how to cite" into the README (#69) (@engintoklu)
• Include CMA-ES into the README (#57) (@NaturalGradient)