improved test-zstd-speed.py
improved test-zstd-speed.py

1. Logs are much smaller now
2. Added "--message"
3. Added autodetection of mutt and mail

inikep/zstd,inikep/zstd,Majlen/zstd,Majlen/zstd,Cyan4973/zstd,Cyan4973/zstd,Cyan4973/zstd,ds77/zstd,inikep/zstd,ds77/zstd,inikep/zstd,Cyan4973/zstd,ds77/zstd,Majlen/zstd,Majlen/zstd,Cyan4973/zstd,ds77/zstd