* change fee to fee_fields in various structs and fix tests for new fee calculation
* set up accept_fee_base param in grin-wallet.toml
* fix bug and adopt new tx_fee interface
* Fix doctests
* Remove left over debug statement
* revert field name feef to fee to remain slate compatible
* use into() for some literal fee_fields
* add height arguments to FeeFields methods where necessary
* Fix tests
* Rename fee_fields -> fee on Context
* Rename fee_fields -> fee on TxLogEntry
* Update to grin master
* replace fee(0) by fee(2*YEAR_HEIGHT) to get fee masking
* Fix compilation error and revert Cargo lock
* fix wrong height passed into next_difficulty
Co-authored-by: Jasper van der Maarel <j@sper.dev>