Dino dex

Refactored code and cleaned up arrowheads following discussion with Dan
i'd also argue for dropping the `map`(s) entirely and just returning `filtered_dinos`. it shouldn't be this method's responsibility to convert the results to a printable string format -- it should only be concerned with filtering dinos. plus if you implement `Dino#to_s`, then a simple `puts filter_dinos(filters)` will suffice anyway.