Add support for SOCKS proxy

[IonCimpoiesu]

Hello,

Thank you for your hard work. I'd like to suggest adding support for SOCKS4/5 proxy to the API. This could be especially useful for those who need to download large quantities of tick data and want to parallelize the process for multiple market instruments or reduce the total download time.

For example, estimating the time to download tick data for XAUUSD from 2010 to today, using a reasonable batch size and pause between batches to avoid getting IP banned by Dukascopy, it could take 2-3 days.