Removed std::random_shuffle

The random_shuffle(first, last) and random_shuffle(first, last, rng) functions were marked already as deprecated in C++14. The reason was that in most cases it used the rand() function, which is considered inefficient and even error-prone (as it uses global state). Alternatively, you could provide the rng function parameter that appeared to be unusable in practice. If you need the same functionality, use std::shuffle:

template< class RandomIt, class URBG >
void shuffle( RandomIt first, RandomIt last, URBG&& g );

std::shuffle takes a random number generator as the third template argument, which is safer, easier to use and more scalable.

Have a look at the following example on how to convert from random_shuffle to shuffle: