optimized array operations

[bearophile]

Eugene Pelekhay:
> however major code differcence will be in benchmark function wich is
> not intended for inclusion in librariy

In my libs I keep the tidy benchmark code too (and few timing tables too), because it's part of the performance benchmarking of the code, so it completes the unittests, spotting performance problems, etc.

Bye,
bearophile