Perfomance: unnecessary rerendering

Hi. First of all thanks for your work!

But here's i investigate some perfomance issues. I'm currently using `why-did-you-render` lib and have some interesting warnings:


(another 3 warns is the same)

I believe `react-composer` changing component's children more than 1 time so it's produces some unnecessary rendering. Here I have 4 rerenders due to `props.children` !== `prevProps.children`

Thanks.

Start by reproducing the reported warnings with why-did-you-render and inspect how react-composer updates props.children. Use the linked warning image and the report of four rerenders as the baseline; done means the unnecessary children-driven rerenders are no longer observed.

Written by the indexing model from the issue text.