Machine-friendly Trade Logs

[tiberio-baptista]

In addition to polldata.json, I think it would be beneficial to have a separate log with machine-friendly trade logs (JSON line format, see https://jsonlines.org/). This seems easy to implement, and this feature could be toggled via options.json or an environment file.

Benefits
An example of this being useful: the file could be easily monitored for new logs, and new lines would be easily parsed and fed to software that can generate graphs and charts, such as Grafana with a Loki backend.

Other use-cases can be thought up of, such as custom alerts to alternative apps/software such as Telegram, Slack, e-mail, (...). Another example is that self-made GUIs could be able to update their visuals/charts in real-time by simply monitoring this file.

Alternatives
This could be done with polldata.json, but I don't find this practical because the whole file must be read and parsed for new trades. polldata.json also tends to increase in size, making each subsequent read/parse of the entirety of the file more costly.