String replace optim

Hi,

I removed my adaptive variant and further tuned interaction with horspool search by removing the enum overhead and replacing the int array shift table by a string abused as uint8 array.

Also I added benchmarks to compare simple find with horspool find and improved the benchmarking code and output to be more instructive.

Adaptive behaviour could still be of value, but the right place for this would be the find_from code.
===> DONE in commit 8f01fd7

Cheers,

Christopher