add hftbacktest and lakeapi

[leftys]

Hi, I propose adding hftbacktest and lake-api:

• hftbacktest is great backtesting tool working on order book data with good precision and performance (thanks to numba jit compilation)
• lake-api is API for downloading high-frequency order book and trade cryptocurrency data. it's probably the most accessible way to get historical order book data. (disclosure: i am its author)