New shell scripts for testing, used for travis CI (#957)

Perform more complex verification and validation.

- signature.sh : extract and optionally compare Bench/Signature/Node count.
- perft.sh : verify perft counts for a number of positions.
- instrumented.sh : run a few commands or uci sequences through valgrind/sanitizer instrumented binaries.
- reprosearch.sh : verify reproducibility of search.

These script can be used from directly from the command line in the src directory.

Update travis script to use these shell scripts.

No functional change.