6% speed improvement

[ghost]

Further improvements could be: not restarting stockfish everytime. I did this in my own program and it made it 131x faster.

[fsmosca]

With this change
bufsize=1
it will no longer run on python 2 and 3, on windows.

[fsmosca]

Regarding the removal of
p.stdin.write("ucinewgame\n")

I don't really like this, in uci protocol it is always preferable to send that command to the engine specially when chess artist is used in epd processing.

On the other hand if chess artist is used in game analysis, not sending ucinewgame is reasonable as positions there could be related, but this is really not practical as the engine is quitted after every position analysis.