CROSS-keccak-times4

Adds the parallel and incremental version of Keccak to the signature scheme CROSS and measures the difference in signing and verifying speed.

Test setup:

CPU: Intel(R) Core(TM) i7-6500U CPU @ 2.50GHz
Battery: plugged in, not charging

Run speed test:

Build:

cd Additional_Implementations/Benchmarking/
rm -rf build
mkdir build
cd build
cmake ../
make
cd ..

Set CPU frqeuency to min until the next reboot:

sudo cpufreq-set -c 0 --min 400000 --max 400000
sudo cpufreq-set -c 1 --min 400000 --max 400000
sudo cpufreq-set -c 2 --min 400000 --max 400000
sudo cpufreq-set -c 3 --min 400000 --max 400000

Collect results:
```
./bench_all.sh
```

TODO:
- in csprng_hash.h setup unique API for hashing and csprng
- verify the usability of SHA_3_LIBKECCAK in sha3.h
- add ifdefs to only use parallel keccak when compiling for avx2