Scripts to download BookTicker data

Hey guys, I see that bookticker data is available online via https://www.binance.com/en/landing/data here and I'm wondering if any official binance developer can provide a file to download bookticker data such as download-aggtrade.py. If this is not in your priority, I'll do it on my own and push it to this repo someday.

Review the existing download-aggtrade.py script and the Binance historical-data page linked in the issue. Before implementation, clarify the expected BookTicker coverage, inputs, output files, and whether this repository is the intended home; done should mean those requirements are documented and the downloader's scope is agreed.

Written by the indexing model from the issue text.