Add more operations

[jonatanklosko]

Not all operations are practical to implement them on tensors, but I'm positive we can add these:

• [ ] random selection (with and without replacement, configured via an option)
• [ ] clip (reducing all genomes to a specific range, useful for real representation)
• [ ] shuffle (shuffling rows in the population matrix, useful when using natural_selection to randomize parent pairs)
• [ ] two point crossover
• [x] n-point crossover (ideally without point collisions; this is pretty much a generalized two point crossover, but I think we can implement two point crossover more efficiently) (#27)