stoikov: Remove biased midquote rounding

Signed-off-by: Aleksi Pitkäjärvi <aleksi.pitkajarvi@aalto.fi>
stoikov: Move simulate() to own file

Signed-off-by: Aleksi Pitkäjärvi <aleksi.pitkajarvi@aalto.fi>
stoikov: Remove duplicated code in plot.cpp

Signed-off-by: Aleksi Pitkäjärvi <aleksi.pitkajarvi@aalto.fi>
stoikov: Move initial spread update to constructor

Signed-off-by: Aleksi Pitkäjärvi <aleksi.pitkajarvi@aalto.fi>
stoikov: Add option to dump inventory at end of run

Signed-off-by: Aleksi Pitkäjärvi <aleksi.pitkajarvi@aalto.fi>
stoikov: Streamline Portfolio interface

Signed-off-by: Aleksi Pitkäjärvi <aleksi.pitkajarvi@aalto.fi>