bug#56521: Add 'take' list operation [PATCH]

[Mattias Engdegård]

Not much argument here; pushed to master. A couple of notes:

I went for the C implementation of `ntake` because I already had the code, and 
because an elisp implementation would be slower than `take` for short lists or 
small N, and there very point of `ntake` is speed.

`nthcdr` has some elaborate code for handling bignum arguments which makes some 
kind of sense since it's defined as an iteration of `cdr`. Currently, `take` 
and `ntake` require fixnums because bignums didn't seem to be worth the trouble.

Before closing the bug, I'll make the new code pay their way by adding some 
calls. `seq-take` is first in line for a makeover.