Suggested additions to the "swiss army knife"

[wellcaffeinated]

Here are some functions i think would be great to add to the library:

• dropLast(n): buffer the last n values and once the iterator completes, drop them. Release the rest on the fly.
• dropWhile(predicate): skip values until predicate(value) returns true
• enumerate: maps input value to [index, value]
• find(predicate): drops values until predicate(value) returns true, then yields that single value and ends
• nth(n): drops values until the nth value is reached then yields that single value and ends

Additions for higher order functionality:

• zip( iterators[] ): normal zip functionality. yields arrays containing values from each iterator until all iterators end.