Support crypto currency transactions

[ttfra]

I was able to use --raw option to create a report for my crypto currency transactions with fiat money.

However there seems to be no support for crypto-to-crypto transactions (e.g. converting BTC to USDT counts as a disposal as per HMRC).

[vmartinv]

This is a nice feature. If you want a short-term solution, split each crypto-to-crypto transaction into a sell and a buy manually in the csv (this is actually how we should do it in the calculations).

Implementing this in the code still requires us:

1. Add support for EXCHANGE transaction type
2. Fetch the value of the two coins being exchanged, or add support to provide it in the csv (we need both values)
3. Add support for fees that are not in the same currency as the other two coins (i.e. BTC to USDT using BNB fees). This will also require fetching the value of the fees in £.

In my case even after adding this is still too hard, I have 20 wallets across different blockchains and exchanges and is hard to tell apart inter-wallet transfers vs exchange conversions vs staking vs pool interest. I'm happy if we provide this basic support at least.