Cull an array to every n-th element.

I work with time series data quite often and I find myself writing something like the following regularly; I wonder if it's worth adding as a core method, supporting objects, optimizing for better performance internally (especially with the _rtl option). If interested, I am happy to expand and work on a related PR.

See: https://github.com/lodash/lodash/issues/706

All credits go to @kurttheviking