ftx - checksum orderbook limit

[pcriadoperez]

Bug: When using a limit the checksum fails.

This was copied from PR - https://github.com/kroitor/ccxt.pro/pull/391/files

• @frosty00 mentioned "this solution is slightly inefficient because it limits on every update. will try to come up with a better solution for this soon"

In my opinion this solution works, but I agree with @frosty00 , that it isin't the most efficient. The other solution I can think of, is using the hidden values stored in the orderbook for the checksum, by either making public or allowing to pass a checksum function to the orderbook object.

Thoughts?

[carlosmiei]

@frosty00 can we merge this until a better solution is found?

[frosty00]

i think that I want to redo the orderbook limiting code so that we don't emulate the limiting and only send it to an exchange as a parameter