Bug Fix: Saving of "alpha_code" when creating a new city
Bug Fix: Returning to correct city after editing a financial transaction
New method "type_to_nicename", returns human-readable and translateable transaction type
Modified method "get_tax_rate", added exit points for invalid input & output values, fixed callback parameters
Tweaks of Excel workbook generation, most importantly Formulae
Further spreadsheet tweaks: Added city column when grouping by country, modified call to "get_transactions" method, fixed minor logical bugs
New method "delete_account"
Added call to financial account deletion method when deleting a geographical unit