Rp2

* added crypto_fee to InTransactions (by popular demand): previously in-transaction fee would only accept fees in fiat, but in certain situations fee is paid in crypto (e.g. crypto conversion, etc.). With this fix, either crypto_fee or fiat fee can be assigned (not both). If fiat_fee is assigned, crypto_fee is set to 0. If crypto_fee is assigned, fiat_fee is set to crypto_fee * spot_price. The reason for this behavior is that if the fee is paid in fiat, then no crypto is used for the fee, but if the fee is paid in crypto, then its converted fiat value is needed to compute taxes. Note that RP2 models a non-zero crypto_fee with a separate fee-typed out-transaction.
* added new unit test for the new InTransaction crypto_fee (input/test_data4.ods)
* updated documentation to reflect new features from this release
* added a new FAQ on crypto rewards and reworded various answers.

* added fee-only transactions: this type of transactions occur in certain DeFi scenarios (see [relevant FAQ](https://github.com/eprbell/rp2/tree/main/docs/user_faq.md#how-to-handle-fee-only-defi-transactions) for more)
* added documentation of transparent computation, including one new FAQ on how to verify RP2 tax computation results: https://github.com/eprbell/rp2/blob/main/docs/user_faq.md#how-to-verify-that-tax-computation-is-correct
* minor edits to documentation

* added new FAQs
* added pointers in documentation to DaLI, the data loader and input generator for RP2: https://github.com/eprbell/dali-rp2

* improved error message when ods_parser._process_constructor_argument_pack tries to parse a numeric argument and fails because the value is not numeric

* added an extra check in IntraTransaction constructor: if spot_price == 0 and fee > 0 then raise an error (because the fiat value of the fee cannot be computed)
* minor edits to documentation

* in the tax_report_us output the following tabs had the description field mistakenly hidden: Airdrops, Income, Interest, Mining, Staking, Wages. All other tabs didn't have the problem. The hidden field is now visible
* the unique_id field (containing hash or exchange-specific id) is now generated in the output files (both tax_report_us and rp2_full_report)